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Messages posted by: wildcard
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In a 2nd December 2019 article at Phys.org, Bob Yirka reports on an
interesting finding uncovered by pouring through data from
Australia's Desert Fireball Network.

An extremely slow fireball (codename DN160822_03) with an initial velocity
of around 11.0 km/s was detected by six of the high-resolution digital
fireball observatories located in the South Australian region of the
Desert Fireball Network.

By integrating its orbit, researchers say the object had probably
orbited Earth as a "minimoon" prior to reentry.

Bob Yira, Phys.org wrote:
A team of researchers at Curtin University studying data from Australia's Desert Fireball Network has identified a minimoon fireball. In their paper published in The Astronomical Journal, the group describes how they found the fireball and the methods they used to show that it had come from a minimoon.

As the researchers note, space objects that make their way close to Earth but do not immediately get pulled in by gravity are known as temporarily captured orbiters (TCOs), natural Earth satellites, or simply minimoons. Such objects circle the planet rather than plunge through the atmosphere and into the ground—at least for a time. It is believed most such objects do not circle the Earth for very long—they eventually succumb to gravity and crash through the atmosphere, or are instead flung back into space. As the researchers also note, to date only one such object has ever been recorded circling the Earth—an object named 2006 RH120 was spotted back in 2006 circling the planet—it did so for approximately 11 months before it escaped the Earth's gravity and made its way back into space. Also, only one minimoon fireball has ever been observed—a team running a camera network in Europe spotted one back in 2014. In this new effort, the researchers report a second identification of a TCO blazing through the sky as a fireball prior to hitting the ground.

The researchers found evidence of the fireball by pouring through data from Australia's Desert Fireball Network—a system of cameras (that also captures flight path) set up across the country for the specific purpose of capturing photographic evidence of a minimoon fireball. To find evidence of such a fireball, the researchers studied the photographs looking for evidence of any type of fireball, be it from a meteor or a TCO. Once found, the team used the flight path data to calculate the trajectory of the blazing object—objects circling the Earth before streaking through the atmosphere will have come in at a smaller angle.

The researchers suggest it is likely more such objects will be found in the coming years as more interest in them mounts—they represent an opportunity to capture a space object in its native state.

Article, map here :-

"Identification of a Minimoon Fireball" by Shober et. al, abstract,
THe Astronomical Journal :-
In a November 28, 2019 article at The Conversation, Roberto Soria,
a professor at the Sydney University of Sydney School of Physics,
discusses a mystery around the origin of a black hole dubbed LB-1,
which is about 15,000 light years away and is about 70 times as heavy as
the Sun.

Roberto Soria wrote:
This is very surprising for astronomers like me. The black hole seems too big to be the product of a single star collapsing, which poses questions for our theories of how black holes form.

Roberto Soria wrote:
What’s normal for a black hole?

Astronomers estimate that our galaxy alone contains about 100 million black holes, created when massive stars have collapsed over the past 13 billion years.

Most of them are inactive and invisible. A relatively small number are sucking in gas from a companion star in orbit around them. This gas releases energy in the form of radiation we can see with telescopes (mostly X-rays), often accompanied by winds and jets.

Until a few years ago, the only way to spot a potential black hole was to look for these X-rays, coming from a bright point-like source.

About two dozen black holes in our galaxy have been identified and measured with this method. They are different sizes, but all between about five and 20 times as heavy as the Sun.

We generally assumed this was the typical mass of all the black hole population in the Milky Way. However, this may be incorrect; active black holes may not be representative of the whole population.

Roberto Soria wrote:
LB-1 is the first major result of our search with LAMOST. We saw a star eight times bigger than the Sun, orbiting a dark companion about 70 times as heavy as the Sun. Each orbit took 79 days, and the pair are about one and a half times as far away from each other as Earth and the Sun.

Roberto Soria wrote:
Where did it come from?

How was LB-1 formed? It is unlikely that it came from the collapse of a single massive star: we think that any big star would lose more mass via stellar winds before it collapsed into a black hole.

One possibility is that two smaller black holes may have formed independently from two stars and then merged (or they may still be orbiting each other).

Another more plausible scenario is that one “ordinary” stellar black hole became engulfed by a massive companion star. The black hole would then swallow most of the host star like a wasp larva inside a caterpillar.

The discovery of LB-1 fits nicely with recent results from the LIGO-Virgo gravitational wave detectors, which catch the ripples in spacetime caused when stellar black holes in distant galaxies collide.

Full article here :-

"A wide star–black-hole binary system from radial-velocity measurements"
by Liu et. al. Nature, abstract :-
Kenneth Chang, New York Times, 25 Nov 2019 wrote:
Jupiter’s Great Red Spot is shrinking, but that does not necessarily mean that it is dying.

Earlier this year, amateur astronomers caught the red spot seemingly starting to fall apart, with rose-colored clouds breaking away from the storm that is some 15,000 miles wide. In May, giant streamers of gas appeared to be peeling from the spot’s outer rim, blown into the winds circling the planet.

The spot — which is red for reasons not fully understood — has become smaller in recent decades. Some Jupiter-watchers wondered if they were witnessing the beginning of the Great Red Spot’s end.

“We beg to differ with that conclusion,” Philip S. Marcus, a professor of fluid mechanics at the University of California, Berkeley said on Monday during a news conference at a meeting of the American Physical Society’s division of fluid dynamics in Seattle. In essence, Dr. Marcus said, the odd dynamics in the spot are just the result of weather on Jupiter, the solar system’s largest planet.

Story here :-

Abstract :-
In a November 15th 2019 press release, NASA have announced that :-

NASA wrote:
Even by the wild standards of the outer solar system, the strange orbits that carry Neptune's two innermost moons are unprecedented, according to newly published research.

Orbital dynamics experts are calling it a "dance of avoidance" performed by the tiny moons Naiad and Thalassa. The two are true partners, orbiting only about 1,150 miles (1,850 kilometers) apart. But they never get that close to each other; Naiad's orbit is tilted and perfectly timed. Every time it passes the slower-moving Thalassa, the two are about 2,200 miles (3,540 kilometers) apart.

In this perpetual choreography, Naiad swirls around the ice giant every seven hours, while Thalassa, on the outside track, takes seven and a half hours. An observer sitting on Thalassa would see Naiad in an orbit that varies wildly in a zigzag pattern, passing by twice from above and then twice from below. This up, up, down, down pattern repeats every time Naiad gains four laps on Thalassa.

Although the dance may appear odd, it keeps the orbits stable, researchers said.

"We refer to this repeating pattern as a resonance," said Marina Brozović, an expert in solar system dynamics at NASA's Jet Propulsion Laboratory in Pasadena, California, and the lead author of the new paper, which was published Nov. 13 in Icarus. "There are many different types of 'dances' that planets, moons and asteroids can follow, but this one has never been seen before."

Far from the pull of the Sun, the giant planets of the outer solar system are the dominant sources of gravity, and collectively, they boast dozens upon dozens of moons. Some of those moons formed alongside their planets and never went anywhere; others were captured later, then locked into orbits dictated by their planets. Some orbit in the opposite direction their planets rotate; others swap orbits with each other as if to avoid collision.

Neptune has 14 confirmed moons. Neso, the farthest-flung of them, orbits in a wildly elliptical loop that carries it nearly 46 million miles (74 million kilometers) away from the planet and takes 27 years to complete.

Naiad and Thalassa are small and shaped like Tic Tacs, spanning only about 60 miles (100 kilometers) in length. They are two of Neptune's seven inner moons, part of a closely packed system that is interwoven with faint rings.

So how did they end up together — but apart? It's thought that the original satellite system was disrupted when Neptune captured its giant moon, Triton, and that these inner moons and rings formed from the leftover debris.

"We suspect that Naiad was kicked into its tilted orbit by an earlier interaction with one of Neptune's other inner moons," Brozović said. "Only later, after its orbital tilt was established, could Naiad settle into this unusual resonance with Thalassa."

Brozović and her colleagues discovered the unusual orbital pattern using analysis of observations by NASA's Hubble Space Telescope. The work also provides the first hint about the internal composition of Neptune's inner moons. Researchers used the observations to compute their mass and, thus, their densities — which were close to that of water ice.

"We are always excited to find these co-dependencies between moons," said Mark Showalter, a planetary astronomer at the SETI Institute in Mountain View, California, and a co-author of the new paper. "Naiad and Thalassa have probably been locked together in this configuration for a very long time, because it makes their orbits more stable. They maintain the peace by never getting too close."

The research is available to read and download here: -


Royal Astronomical Society wrote:
A rare transit of Mercury will take place on 11 November, when the smallest planet in our Solar System will pass directly between the Earth and the Sun. The last time this happened was in 2016, and the next will be in 2032. During the transit, which takes place in the afternoon in the UK, Mercury will appear as a dark silhouetted disc set against the bright surface of the Sun.

The transit begins at 1235 GMT, when the edge of Mercury appears to touch the edge of the Sun, and ends at 1804 GMT when the edge of the silhouetted planet appears to leave the Sun. Observers in different locations will see the transit taking place up to 2 minutes before or after these times, as the planet will appear to take a slightly different path across the Sun.

On the morning of 11 November, UK amateur astronomical societies and public observatories will be running events where members of the public can safely enjoy the transit, as well as live webcasts of the spectacle. The Royal Astronomical Society will be supporting a (free) event run by the Baker Street Irregular Astronomers in Regent’s Park, central London, where members of the public can book places to come and view the transit using appropriate equipment at no cost.

Professor Mike Cruise, President of the Royal Astronomical Society, is keen for people to experience the transit for themselves. "This is a rare event, and we’ll have to wait 13 years until it happens again. Transits are a visible demonstration of how the planets move around the Sun, and everyone with access to the right equipment should take a look, or go to an organised event if the weather is clear, or alternatively follow one of the live webcasts. I do want to stress though that people must follow the safety advice – looking at the Sun without appropriate protection can seriously damage your eyes.”

The entire event is visible from the eastern United States and Canada, the south-western tip of Greenland, most of the Caribbean, central America, the whole of South America and some of west Africa. In Europe (including the UK), the middle East, and most of Africa, the sun will set before the transit ends, and so the latter part of the event will not be visible. In most of the United States and Canada, and New Zealand, the transit will be in progress as the sun rises. Observers in eastern Asia, southern and south-eastern Asia, and Australia will not be able to see the transit.

Mercury completes each orbit around the Sun every 88 days, and passes between the Earth and Sun every 116 days. As the orbit of Mercury around the Sun is tilted compared with the orbit of the Earth around the Sun, the planet normally appears to pass above or below our nearest star. A transit can only take place when the Earth, Mercury and the Sun are exactly in line in three dimensions.

There are 13 or 14 transits of Mercury each century, so they are comparatively rare events, though each one can typically be seen over a large area of the Earth's surface. A transit was first seen in 1631, two decades after the invention of the telescope, by French astronomer Pierre Gassendi.

At any time, Mercury blocks out no more than a tiny part of the light from the Sun. This means that the event should NOT be viewed with the naked eye. Looking at the Sun without appropriate protection, either during the transit, or at any other time, can cause serious and permanent damage to the eyes.

The Society for Popular Astronomy has an online guide on how to safely view the transit, for example by projecting the solar image with binoculars or a telescope. Mercury is too small to be visible using the pinhole projectors that worked successfully in the solar eclipse in March 2015, and similarly cannot be seen by using ‘eclipse glasses’ with solar filters.

Observers with access to a moderate-sized telescope with an appropriate safe filter should be able to see Mercury as a dark disc, comparable in apparent size to a sunspot, but somewhat darker. At the beginning and end of the transit, when Mercury's limb is close to the edge of the Sun, it may also be possible to see the 'black drop' effect, where a broad line appears to connect the planet to the solar limb. This is thought to result from the quality of the telescope in use, and turbulence in the Earth's atmosphere (so-called 'seeing'), and has in the past compromised efforts to record transit times.

As it is so close to the Sun, Mercury is difficult to study in detail using telescopes on Earth. Two NASA space probes have visited Mercury, Mariner 10 in 1974 and 1975, and MESSENGER, which orbited the planet from 2011 until a deliberate crash landing in 2015. The European Space Agency mission BepiColombo launched in 2017, and is expected to study the planet from 2024 onwards. UK scientists are making a significant contribution to this project.

Transit techniques are also deployed to study objects outside our Solar System, and for example missions like the NASA Kepler space telescope used it to confirm the presence of 2,662 planets in orbit around other stars. The same technique will be used by the European Space Agency's PLATO mission, expected to launch in 2026.

Press release here :-
moebius9 wrote:I am not very young and after some hours staying at the eyepiece, I feel tired.
So, I would like to sit down and go on observing on the screen of my PC. The goal is not to make great images, but just to see the object I aim at.
I have to learn how to use Argo Navis through a planetarium on the PC. I have the cable to connect the PC at the AN unit.


Hi Michell,

Irrespective of age, I think all of us, sometimes, when observing with a group of friends and waiting for your turn at the eyepiece, find it hard to get up out of the chair late at night once you get comfortable. smilie

Have you explored what camera/imaging system you might use yet?
One of the more powerful features of Argo Navis is its in-built Telescope Pointing Analysis System (TPAS).

Most users will never need it.

However, there are some that do.

The definitive reference to using TPAS is the User Manual in the section on SETUP MNT ERRORS.
See http://www.wildcard-innovations.com.au/documentation.html

However, sometimes user's ask whether a tutorial is available and I have emailed them this response which appears below.


There is a reasonable amount to absorb initially but based on working hands-on with many customers, I assure you after a few runs it will become intuitive.

Firstly, I encourage you to spend some time browsing the submenus beneath SETUP MNT ERRORS.

These sub-menus are as follows -

ACQUIRE DATA - switch SAMPLE MODE=ON to enable pointing test sampling
COMPUTE ERRORS - will attempt to fit the pointing model defined in DEFINE MODEL
DEFINE MODEL - used to define which error terms will be fitted by COMPUTE ERRORS
REVIEW DATA - used to examine raw and fitted pointing data residuals along with total raw and fitted RMS. Also allows for deletion of samples.
SET ERROR VALUES - two submenus beneath this -
IN USE NOW - allows one to examine and manually modify mount error terms currently in use by the pointing kernel
SAVED IN NVRAM - allows one to examine and manually modify mount error terms saved in non-volatile memory for later sessions

In a nutshell, you will want to enter your various SETUP parameters as before.
Set DATE/TIME LOCATION as horizon and pole checking is performed.
Highly recommend that you set REFRACTION=ON

If you have an Argo Navis serial port free, have it startup with the navis command before
you begin the pointing test. You will then be able to dump the data for analysis by Wildcard.

As you will see later, when SAMPLE MODE=ON, a new submenu is enabled when you press ENTER in GUIDE mode.
This new submenu has a selection of DESCRIPTION or SAMPLE MNT ERROR.
When DESCRIPTION appears, if ENTER is pressed, scrolling object description appears as in previous firmware.
When SAMPLE MNT ERROR appears, if ENTER is pressed, object position is sampled.

To preform pointing test, Ideally install reticle or reasonable power eyepiece.
Always center stars as accurately as possible to reduce error.

Perform FIX ALT REF (AUTO ADJUST ON is OK to use) and two-star alignment as before.

Only sample (bright - 6th mag or brighter) stars (ideally those that appear in bright star catalog) or planets.

Use MODE IDENTIFY or MODE TOUR to select a bright star. Suggest start with last alignment star.
When GUIDE appears, press ENTER. When DESCRIPTION appears,
spin DIAL until SAMPLE MNT ERROR appears. Center star/planet in reticle. Press ENTER.
Argo Navis will report pointing residual.

Then suggest sample first alignment star as above.

Sample two more stars. Thus you have so far sampled 4 stars in all.
This is sufficient for you to perform an initial fit.

Press ENTER. Argo Navis will report Root Mean Square (RMS) and Population Standard
Deviation (PSD) of fit. Don't expect any improvement yet. All values are in arc minutes.
Argo Navis will also report IE=XXX where XX.X is the computed value for the fit of the index error in elevation (Alt)
Press ENTER to USE TERM and return to pointing test.

Sample one or two more stars.

Press ENTER and set NPAE=COMPUTE. Press EXIT twice.

Argo Navis will now also attempt to fit for Az to Alt axes not being orthogonal (NPAE).
Take note if RMS and PSD have reduced from before. Take note of standard
deviation of NPAE term (the number after the +/-). Only accept (i.e. USE NOW) if value of term
is at least two or three times larger than its standard deviation.
Acceptance of all terms can also be aborted by pressing EXIT.
Assuming NPAE looks real, press ENTER a few times to accept IE and NPAE as USE NOW.

You can review your pointing test data at any time.
To review pointing data, select REVIEW DATA.
Last sampled point appears as default. Spin DIAL anti-clockwise to view earlier samples.
Large DELTA (triangle) means raw pointing residual.
Spin DIAL fully clockwise until END OF DATA and examine RAW RMS.
Press ENTER and change to DELTAS=FITTED. Press ENTER or EXIT.
Display now shows FIT RMS. Small delta symbol (d) means fitted residual.
Spin DIAL anti-clockwise to examine residuals of samples for the current model in use now.
To delete an item, press ENTER. To delete all items, go to START OF DATA and press ENTER.

Now sample some more stars. Try and take samples with good spread in Alt and Az (i.e. whole sky).
System will not allow to sample star unless 10 degrees above horizon. System will
not allow star to be sampled too close to zenith. Probably best to avoid sampling greater than 85 degrees in Alt.

Use DEFINE MODEL to experiment with other error terms, such as left-right collimation
error (CA) and the two eccentric terms (ECEC and ECES). ECES also accounts for truss tube flexure.
As rule of thumb, probably need about 15 stars with good distribution in Alt to
first characterize CA as it is hard to distinguish from NPAE. Probably need 20 to 100 stars
to more reliably determine NPAE, CA, IE, ECES and ECEC. Suggest always accept IE even if standard
deviation appears larger than value itself.

Think of DEFINE MODE and COMPUTE as a work-bench where you can experiment with
different terms and see if they improve your pointing.
Basically you want to add or remove combinations of terms from within DEFINE MODEL
and then go back and COMPUTE. If the RMS and in particular the PSD does not drop, just press EXIT
and go back to DEFINE MODEL and try again. Normally you will always want to use IE and possibly NPAE.
Sometimes you will also want CA or maybe CA in place of NPAE and maybe ECEC and/or ECES.

If you want to save terms for the next session, never save IE. NPAE, ECEC and ECES are generally
persistent on many mounts and OK to save. CA can vary from session to session with collimation,
eyepieces, etc, so it may not be worth saving. To save terms, when the system gets to the point where
it says USE NOW after pressing ENTER in COMPUTE, you can change USE NOW to USE NOW & SAVE.
During a subsequent observing session you can fix terms line NPAE, ECEC and ECES in
DEFINE MODEL as a constant value. Just spin the DIAL from COMPUTE to the constant value.
By fixing terms, on a subsequent observing run, you can perform a much shorter pointing
run, maybe (4 to 5 stars, which) allows you to nail IE and CA as well as some index error
and tilt terms that are internal to the system but not reported.

As a rule of thumb, if you have 10000 step encoders, that is equivalent to about 2.1' per encoder step.
We have used some mounts where we can get RMS results around 2.1'. In other words, that value
gives you some feel for about as good as you can get when the system becomes encoder resolution
limited. However, we have seen some mounts where the RMS value can be higher, particular if there
are other unmodeled phenomena occurring or non-systematic (i.e. random) behaviour such as the top-end
suddenly moving on the truss poles if it were not tightened properly.

I will also provide here some additional information on the information that is reported to
you whenever you sample a star in GUIDE mode.

Whenever you sample a star, the system will show for 2 seconds how many
stars you have sampled (ITEM= and what the pointing residual was in degrees, arc minutes or arc seconds
for that sample. Like ALIGN mode, you can re-sample if your eye-finger co-ordination was out.

Currently we only allow a star to appear once in the sample data. If you come back
and re-sample, you replace the original datum point.

When you sample a star in GUIDE mode, the delta it reports is always for the current pointing model you have in place.
It you have no pointing model in place, a big DELTA (Greek Triangle=) will be reported.
If you have a pointing model in place, a little delta (Greek d=) will be reported.
The current pointing model is defined by your alignment and whatever values appear in the

The nice thing is that when you start the pointing test, before you have fitted a model,
the DELTA reported is your raw pointing. Once you fit a model, the deltas are now those for
when the model is applied. In other words, you start to get some feedback about how your pointing
might be improving (or getting worse) as you sample each new part of the sky. An increasing pointing residual
on a star in some new part of the sky is often a good prompt to go back and COMPUTE again
and update the pointing model.

You can also always use REVIEW DATA to examine the pointing data as both RAW and FITTED.
If when examining FITTED data you notice one sample that sticks out with a very large residual
that you suspect was mis-identified, consider deleting it. Just press ENTER and the ENTER again.
However, don't get "trigger happy" when deleting an item. Sometimes the star might really
have some large pointing residual at it is a glimpse of it telling you that possibly some additional pointing terms
need to be added or something has possibly physically changed.

An introduction to standard deviation and a case study.

The following additional information may be helpful. It was written
in response to a question from a customer who asked about the
significance of the standard deviations Argo Navis reports on each of
the error terms.

It also includes a case study of a pointing test done on a 20" f5 truss pole Dob.


The standard deviation gives some measure of the distribution or 'spread'
of data about the mean. Therefore, when a data item has a small standard
deviation, one would expect most of the values to be grouped around the mean.

Thus, we want the standard deviations to be as small as possible.

Suppose your data follows the classic bell shaped curve pattern.
One conceptual way to think about the standard deviation is that it is a measures of how spread out the bell is.
Shown below is a bell shaped curve with a standard deviation of 1.
Notice how tightly concentrated the distribution is.


Shown below is a different bell shaped curve, one with a standard deviation of 2.
Notice that the curve is wider, which implies that the data are less concentrated and more spread out.


Finally, a bell shaped curve with a standard deviation of 3 appears below.
This curve shows the most spread.


Now let me provide some results from a real telescope, in this case a home-built 20" f5 truss pole Dob.

A pointing test was performed on 30 stars, distributed across the sky.
Though ideally a reticle should be used, in this particular case, no reticle was used, the stars were simply centered in a medium powered eyepiece.

With no terms fitted, the RMS and PSD were as follows -
RMS = 7.5'
PSD = 7.5'
Furthermore, examining the data in REVIEW DATA, the largest raw error on any star
was 16.4'.

When IE and NPAE were fitted the results were as follows -
IE = -0.0' +/- 0.1'
NPAE = +18.5' +/- 1.1'
RMS = 2.2'
PSD = 2.4'

Even though the standard deviation of IE was 0.1, which was larger than its value of 0.0,
we always keep IE.

The value of NPAE looks plausible or 'real' because its value of +18.5' is nearly 17 times
larger than its standard deviation of +/-1.1'
One analogy is to think of a signal (perhaps a radio signal) and then think of noise (perhaps
radio interference or static). Here the +18.5' is the signal and the +/-1.1' is the noise.
We want a large 'signal-to-noise' ratio, which is what we have got.

Now let us attempt to add the term ECES, which can account for a non-centered
Alt axis encoder as well as any tube flexure. The results were as follows -
ECES = +4.4' +/- 1.9'
IE = -3.2' +/- 1.4'
NPAE = 19' +/- 1.0'
RMS = 2.0'
PSD = 2.2'

Notice that the value of ECES is about 2.3 times the value of its standard deviation.
Therefore it looks plausible, but since its signal-to-noise-ratio is low, we would keep
an eye on it. Note how the signal-to-noise on NPAE improved slightly, now 19-to-1.
Also we note that the RMS decreased and most importantly the PSD also decreased.
If the PSD had increased, then the ECES term would probably not be worth keeping.
Notice, by the way, that this mount now has an RMS value that can be considered
close to encoder resolution limited. An excellent result. A quick examination of
the fitted error value residuals in REVIEW DATA also showed that the largest
error on any star had dropped to 3.7'. In fact, further examination showed that
the star that originally showed the largest raw pointing error of 16.4' dropped
down to 20" once fitted!

To continue with this case study, could the overall RMS/PSD be improved further
by adding another term? Let us try adding ECEC. The results we get are -
ECEC = +5.4' +/- 5.3'
ECES = +9.4' +/- 6.1'
IE = -10.1' +/- 8.1'
NPAE = 18.9' +/- 1.0'
RMS = 2.0'
PSD = 2.3'

Note how the signal-to-noise ratio of the new term, ECEC, is very low, nearly 1:1.
This tells us that ECEC doesn't look plausible. Other clues include the fact that the standard
deviations of some of the other terms increased and the PSD also increased.
Therefore, we would reject ECEC.

Finally, let us try and use CA. The results we get are -
CA = 7.7' +/- 8.1'
ECES = 4.4' +/- 1.9'
IE = -3.2' +/- 1.4'
NPAE = +13.3' +/- 6.1'
RMS = 2.0'
PSD = 2.2'

Note how the standard deviation of the CA term is greater than CA itself. It looks like
it is all noise. Notice also how the signal-to-noise ratio of NPAE also worsened to 2.2'.
The RMS and PSD values also did not improve. Adding CA therefore looks as if it
doesn't help and in fact possibly worsens the statistical integrity of the model.
If the pointing test had been extended to include more stars, particularly some additional
stars with altitudes in the range 60 to 80 degrees, it might then have been worth
trying to fit a model using CA again as it may come out of the 'noise'.

Another experiment with the above data is to remove NPAE and just use CA.
The results were as follows -
CA = 25.3' +/- 1.5'
ECES = 4.2' +/- 1.5'
IE = 3.1' +/- 1.5'
RMS = 2.1'
PSD = 2.4'

This model also looks plausible. However, notice that the RMS and PSD values increased
compared to just using NPAE instead of CA. The reason CA could be substituted for NPAE
in this manner to still get a reasonable fit is that the characteristic 'signature' of CA and NPAE
are very similar. Statisticians would say that CA and NPAE are 'highly correlated'.
In fact, we know from additional analysis of this particular data that these two terms have nearly
a 99% correlation in this instance. Therefore, it is probably best to use either NPAE or CA but not both
inthis particular case.

So how does one determine whether the mount's error is NPAE or CA? As mentioned above,
the number of pointing test samples would need to be increased, in particular selecting stars
over a greater range of altitudes, particularly more stars at higher altitudes, in order to 'unravel' the
NPAE and CA terms.

Based on further tests of this particular telescope, it looks as if the NPAE term of
around +19.0' is real and reasonably persistent. That and the ECES value of 4.4' were
saved and used in subsequent observing sessions. On these subsequent runs, the user
performed a short pointing run of typically 4 to 5 stars. In DEFINE MODEL they had -
ECES = +4.4'
NPAE = 19.0'

After performing a COMPUTE and then accepting the model, they were able to
achieve close to encoder resolution limited whole-sky pointing for the rest of the night.

Hopefully the above is helpful to you, the reader.

Think of the DEFINE MODEL and COMPUTE ERRORS menus as a laboratory workbench
where you can hypothesize what the error terms might be in DEFINE MODEL and
then determine their fit in COMPUTE ERRORS. Remember when you can hit EXIT at
any time in COMPUTER ERRORS which will cancel accepting the terms. Typically
a user will go back and forth between DEFINE MODEL and COMPUTE ERRORS in
this fashion, experimenting with various terms.

When performing a pointing test, we recommend to recompute the model often and then
accept it, as it can assist in locating further stars during the pointing test run.

After a while, you will begin to become familiar with the types of values your particular mount produces.
This Excel Spreadsheet was created by "cozens3" and contains a list of all NGC & IC objects that appear in Hartungs. They have been ranked in order of magnitude.
This list originally appeared on the Argo Navis Users' Group.
David Moorhouse in New Zealand kindly produced these lists of Hartung objects in Excel and CSV formats which was published on the Argo Navis Users' Group.

Professor E. J. Hartung first produced a comprehensive and highly respected guide for southern observers in 1968.

This book was then revised in 1995 by David Malin, who was previously the astrophotographer at the Anglo Australian Telescope, and by David Frew, an astronomer at Macquarie University here in Sydney.

This book is cherished by many southern observers and Peter Marples produced an Argo Navis user catalog from the list of objects described in the book.

For anyone new to southern skies, this book and catalog make for a wonderful starting point.
Book details here :-
In a 30 October 2019 press release from the University of California San Diego :-

UCSD wrote:
Exploring the influence of galactic winds from a distant galaxy called Makani, UC San Diego’s Alison Coil, Rhodes College’s David Rupke and a group of collaborators from around the world made a novel discovery. Published in Nature, their study’s findings provide direct evidence for the first time of the role of galactic winds—ejections of gas from galaxies—in creating the circumgalactic medium (CGM). It exists in the regions around galaxies, and it plays an active role in their cosmic evolution. The unique composition of Makani—meaning wind in Hawaiian—uniquely lent itself to the breakthrough findings.

“Makani is not a typical galaxy,” noted Coil, a physics professor at UC San Diego. “It’s what’s known as a late-stage major merger—two recently combined similarly massive galaxies, which came together because of the gravitational pull each felt from the other as they drew nearer. Galaxy mergers often lead to starburst events, when a substantial amount of gas present in the merging galaxies is compressed, resulting in a burst of new star births. Those new stars, in the case of Makani, likely caused the huge outflows—either in stellar winds or at the end of their lives when they exploded as supernovae.”

Coil explained that most of the gas in the universe inexplicably appears in the regions surrounding galaxies—not in the galaxies. Typically, when astronomers observe a galaxy, they are not witnessing it undergoing dramatic events—big mergers, the rearrangement of stars, the creation of multiple stars or driving huge, fast winds.

“While these events may occur at some point in a galaxy’s life, they’d be relatively brief,” noted Coil. “Here, we’re actually catching it all right as it’s happening through these huge outflows of gas and dust.”

Coil and Rupke, the paper’s first author, used data collected from the W. M. Keck Observatory’s new Keck Cosmic Web Imager (KCWI) instrument, combined with images from the Hubble Space Telescope and the Atacama Large Millimeter Array (ALMA), to draw their conclusions. The KCWI data provided what the researchers call the “stunning detection” of the ionized oxygen gas to extremely large scales, well beyond the stars in the galaxy. It allowed them to distinguish a fast gaseous outflow launched from the galaxy a few million year ago, from a gas outflow launched hundreds of millions of years earlier that has since slowed significantly.

“The earlier outflow has flowed to large distances from the galaxy, while the fast, recent outflow has not had time to do so,” summarized Rupke, associate professor of physics at Rhodes College.

From the Hubble, the researchers procured images of Makani’s stars, showing it to be a massive, compact galaxy that resulted from a merger of two once separate galaxies. From ALMA, they could see that the outflow contains molecules as well as atoms. The data sets indicated that with a mixed population of old, middle-age and young stars, the galaxy might also contain a dust-obscured accreting supermassive black hole. This suggests to the scientists that Makani’s properties and timescales are consistent with theoretical models of galactic winds.

“In terms of both their size and speed of travel, the two outflows are consistent with their creation by these past starburst events; they’re also consistent with theoretical models of how large and fast winds should be if created by starbursts. So observations and theory are agreeing well here,” noted Coil.

Rupke noticed that the hourglass shape of Makani’s nebula is strongly reminiscent of similar galactic winds in other galaxies, but that Makani’s wind is much larger than in other observed galaxies.

“This means that we can confirm it’s actually moving gas from the galaxy into the circumgalactic regions around it, as well as sweeping up more gas from its surroundings as it moves out,” Rupke explained. “And it’s moving a lot of it—at least one to 10 percent of the visible mass of the entire galaxy—at very high speeds, thousands of kilometers per second.”

Rupke also noted that while astronomers are converging on the idea that galactic winds are important for feeding the CGM, most of the evidence has come from theoretical models or observations that don’t encompass the entire galaxy.

“Here we have the whole spatial picture for one galaxy, which is a remarkable illustration of what people expected,” he said. “Makani’s existence provides one of the first direct windows into how a galaxy contributes to the ongoing formation and chemical enrichment of its CGM.”

Full press release, pictures, video here :-
Kevin Gill, a software engineer at NASA’s Jet Propulsion Laboratory working on data visualization and analysis projects, has assembled this remarkable short video :-

moebius9 wrote:Hi Gary,

2500m, 2 hours from Nice, the best sky in France !!

The best of both worlds! Close to the sea and to the mountains.
Impressive image! smilie Thanks for posting it as it shows what is possible.
Astromaniac wrote:Hi Gary,
Thanks for replying so promptly. The settings on my AN are correct. So just to clarify: when you say LX200 GOTO you mean (in settings Sky Safari) Telescope Type LX200 Classic and Mount Type Equatorial GoTo (Fork). Is that correct?


Stella Observatory,
Macedon, Victoria,

Hi John,

That is correct.

The Alt-Az. GoTo setting will also do exactly the same but the important thing is the GoTo.

Also on the Sky Safari side, do not check the box that says "Set Time & Location" otherwise if it transmits these parameters, Argo Navis will reset its time and location which will invalidate any alignment you may have made.
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