matt_baker

Is it ramping up again? Just got back inside because it died down for a while

13 hours ago, alacant said:

Hi

Remove the polarscope and cover plate and loosen the cone bearing at the base of RA, rotating the circular nut anticlockwise around, say, 1/10 of a turn at a time, until the axis swings freely. There are three grub screws which bear against the thread to lock it (yeah, I know!!). In between loosenings, give the ra shaft a gentle tap upwards and swing again before retightening.

HTH

 

Just wondering what this does?

5 hours ago, michael8554 said:

Hi Matt

1) Gather all the cables linking equipment on the scope and attach to the scope.

Attach the rest in a smooth loop to the top of a tripod leg.

2) Cals were much better, less backlash in them, accepted by PHD2.

Still showing bunched steps, which is stiction that might have a bearing on the guiding results.

3) Dec Backlash Compensation is still Disabled ?

Which reminds me, if the mount or any software other than PHD2 has any sort of Backlash Compensation, this should be disabled to avoid confusing PHD2.

4) None of your logs show a Guide Assistant run.

This should be a daily operation after a good Cal.

It will suggest settings for that night's conditions, and measure the PA error (no worse than 5arcmins is good enough).

And occasionally tick the "Measure Backlash" box to get a Backlash Comp setting.

5)  For test purposes run the GA for a worm period, so that the mount's PE curve can be inspected.

6) How is the scope balanced ?

East-heavy might help to minimise the overshoots caused by stiction in RA.

Michael

Hi Michael, this was just the guide log from the day after back on the 5th Sept so none of the changes you suggested were applied. Although I did make sure to nudge the mount north that time to cancel any backlash.

I'll make sure to run a long guide assistant and balance it slightly east heavy and see if that helps. I typically balance so nothing moves. I'll measure the backlash too and see what that says

15 hours ago, michael8554 said:

Hi Matt

Overall guiding was good "RA = 0.63 arcsec,  Dec =  0.41 arcsec".

But the Peaks were "RA = 3.38 arcsec,  Dec = -2.17arcsec". 

1) The Calibration threw up a warning  "Last Cal Issue = Difference,"

Guide rates were measured to be "Norm rates RA = 10.9"/s,  Dec = 9.6"/s;"

Probably due to not clearing Dec Backlash before the Cal, PHD2 had to apply 7 steps before Dec started to move.

And see how the RA and Dec pulses are bunched up into pairs and triplets, possibly due to Stiction:

 

2) There are 2 arcsec spikes in Dec that might be due to Backlash.

The log shows  "Backlash comp = disabled, pulse = 932 ms"  ??

3) A few of the frequent RA spikes coincide with Dec spikes.

But most are random.

There aren't any significant fast spikes in the freq analysis, just the 122s one.

So reasons may be due to wind, stiction, cable snags - post a image of the setup ?

Michael

 

 

 

The setup itself has very bad cable management, I've never got round to properly sorting that out.

My power box is located on the side of the mount as I have pretty much no where on the OTA for it to go, as the RPi takes the only space. The cables have to be somewhat long to make sure there's no snagging and ends up ripping off. I make sure when setting up that throughout the whole motion of the mount, there no cables are snagging.

My only solution that I can think of is removing the finder scope from the dovetail and strap both the RPi and power box in its place. My concerns with this are by moving the finder scope back, my dovetail for the telescope won't have any more space to move up as it's already at the limit with the camera being so far back. The other issue is that the main power cable is rather dense and large. This may cause a lot of cable drag as it moves around with the telescope.

I've attached some photos of the setup (don't mind the mess)

Also attached the guide log from the night after the one sent previously. Guiding had to be paused for some of it due to the powerbox falling off. The adhesive decided to give up, so I sellotaped it down as a temp measure. One of the huge dec spikes was the powerbox falling off again, so don't mind that.

PHD2_GuideLog_2023-09-05_220434.txt

Here's 13.7 hours in HOO of the Eastern Veil Nebula but Foraxx palette for more natural stars. The OIII haloing with ZWO 7nm filters isn't the best but was manageable and really not too noticeable thankfully

Ha: 48x480" @ Gain 139

OIII: 55x480" @ Gain 139

Just now, teoria_del_big_bang said:

Nice image 🙂 
Glad you are back imaging I don't think I have done any since March.

Steve 

Thank you, Steve!

Although I can remote into my setup from university, I'm busy most of the time and mainly back in the summer when there's no astronomical darkness so I tend not to bother.

Hopefully will have some spare time this year along with some decent nights!

Been a very long time since I've done some proper imaging but finally back at it, hopefully more to come in the near future.

I decided that the Eastern Veil would be a great target to go for at this time of year.

Here's 13.7 hours in HOO but Foraxx palette for more natural stars. The OIII haloing with ZWO 7nm filters isn't the best but was manageable and really not too noticeable thankfully

Ha: 48x480" @ Gain 139

OIII: 55x480" @ Gain 139

Taken with:

TS Optics 90mm Triplet

ZWO 1600MM Pro

HEQ5 Pro

All processed in PixInsight.

Just taken a look at the frequency analysis and there's a 1.2" spike at 122s. Looking at some other posts, they appear to have a spike at 13.6s and a smaller one at 120-122s.

Although I don't have a spike at 13-14s, is this to do with belt tension perhaps?

There's 9 teeth on the pulley so it makes sense for it to be happening at 122s

Not sure what the much larger spikes are at the end however

I can't tell whether the spikes I'm getting in RA are periodic or random (excluding any dithering events)

Dec seems to be fine for the most part, although that too has spikes (Overcorrecting perhaps?)

Would be greatly appreciated if anyone can take a look at this guiding log and provide any suggestions

PHD2_GuideLog_2023-09-05_002312.txt

Was taking some test shots after adjusting backfocus. Corner stars have improved but don't have enough space on the threads to put anymore delrin spacers so stopped.

Couldn't help but notice that the bottom right of the stars are slightly cut off however there's nothing blocking that should cause that so not sure what may be causing it.

Would anyone be able to help?

Is astrobuysell down for anyone else?

On 27/08/2022 at 11:09, Lambda1974 said:

Hello, 

I have heard  that a new sensor is, or willm occur on the market for astro camera (ZWO, QHY, PLAYER ONE... ?) which is a IMX 462 MM, therefore a mono version of the IMX 462 MC already present and used.

Do you have some infos about this sensor, and about its availability in the market ?

I find such small sensor quite interesting because i guess it would have a tremendous sensitivity in NIR domain, knowing it is already the case with its brother 462MC, and a global very good sensitivity overall (vis + NIR) anyway, without the Bayer matrix.

For DIY project for astro or terrestrial night vision purpose, it would be a good candidate, for hopefully a reasonable budget...

In advance, thank you for your feedback about this.

Best regards and clear skies!

 

Lambda

 

 

Well the sensor was listed on Sony's website in April, so I'd expect there to be cameras potentially on the market around the same time next year or in the summer 

18 hours ago, Froeng said:

Okay, are there concrete pavers around the observatory on that flat roof? If yes, are they all around or are there less in one direction.

I would try to look at the direction where there is less thermal mass present, ie concrete or any other man-made things/buildings. The less the better! Then try to use a star about 60deg from the horizon. The scope has to be as acclimated to ambient as possible. 
if the seeing is still bad, it’s either another day of bad seeing (which do happen about 80% of the time), or it’s the rising heat from the roof/houses. 🤔

It's on a school site so concrete is pretty much surrounding the observatory and there's a lot of buildings facing south where I'm looking most of the time.

I'd say it's probably 50/50 with poor seeing from the atmosphere and buildings. Saying that I did have a look at a star above 60 degrees and it was still dancing all over the shop, I still could barely make out the rings even with it being outside for a couple of hours but that could've been very poor seeing

On 20/07/2022 at 21:32, Froeng said:

Looking at the video of Jupiter you posted, the turbulence is directional, which in my experience indicates it is related to atmospheric seeing. This could be as far away as the Jetstream or it could even be quite close by, ie nearby rooftops. Is the observatory on a flat roof or is it standing on the ground surrounded by buildings? Also, is it a dome with a slit, or does the roof roll off completely?

Tube currents are typically not as directional, and more "swirly" in a SCT, but then all of this is dependent on so many factors, it all depends. Does the telescope cool down after opening the observatory, and if yes, for how long? Or is it air-conditioned to match the outside temperature? Is there a dew shield installed? Are there people in the observatory? You see, there are many questions.

Let's see what the answers are so we can all help to assess the situation.

A first thought might be to use an artificial star during the day to "test" the collimation with less atmospheric interference...

Best Regards

Frank

Observatory is on a flat roof and there are buildings 40m in front, which I can only guess is not helping at all. It's a dome with a slit too.

I'm fairly sure that video was taken a couple of hours after opening, there's only me inside, there's no air con inside there and the dew shield was on.

Forgot to mention also that since it's located on a school site, there's quite a few buildings within where I'd be pointing the scope to the south so I can only assume the heat coming from them is only going to hinder the view further. Although again saying that, when I pointed the scope almost overhead, it was still very bad. Next time it's clear and I'm there, I'll take a quick video on an out of focus star.

I have access to a C14 in an observatory (not mine). I've recently been attempting to use it again, particularly to collimate, but the image I'm getting is that awful. The stars are dancing and flailing around so much even basically overhead that I can't really make out the concentric rings to get a proper gauge what the collimation is actually like. I tried using metaguide and using seeing view but it's still awful. I did forget to take a sample video of what the star looked like but I do have a couple of examples with Jupiter and the Moon

I've heard things like wrapping it in Reflectix to slow down the cooling to prevent heat plumes which is something I might consider. Also the idea of using a Lymax cooler but I do wonder how much better that would be considering the cost.

Has anyone got any recommendations or tips to help?

Here's some footage of what Jupiter and the Moon looked like, although taken at 27 degrees.

Matt

3 minutes ago, tomato said:

I agree, IMHO your rendition is more subtle than the NASA version, and the better for it. You should  email it to them and ask for a job!☺️

I wish! I think the actual job title is 'Science visuals developer'. Dream job right there aha

30 minutes ago, The Lazy Astronomer said:

Hmm, very interesting! I may have a bash at this myself at the weekend. Processing IR data seems appropriate during the hottest weekend of the year. 

Out of curiosity, what was the raw data like to work with? 

It was an absolute treat to work with. No noise reduction needed whatsoever.

The main bit is messing around with the colours since there are 5 channels.

I did have to downsample since a couple didn't have the drizzling applied, not so sure why but made it a lot easier time wise.

Also, the shell script contains every single calibration file and thumbnails which took me an hour to realise that the stitched data I wanted was lying around

Edit: I've just had a look on MAST and the data is now publicly available there as it wasn't earlier. Just search by proposal ID (2731 for Carina) and you'll be able to download the files

48 minutes ago, Sunshine said:

A beautiful rendition, kind of looks better that their rendition, I have to say.

Thank you! Means a lot

Personal rendition of NIRcam NGC 3324 JWST data

Processed in PixInsight

Data can be accessed at the moment via: https://outerspace.stsci.edu/display/MASTDATA/JWST+AWS+Bulk+Download+Scripts

Some more professional sites will have dedicated 'ICC Profiles'.

These are profiles that if your image is in the correct colour space and your monitor is decent and calibrated, you can proof the image for what it would look like when printed.

The 294mc and mm aren't actually the same sensor, just one mono and the other colour.

The MM is an IMX492 and is pretty much identical when binned 2x2 as the IMX294

HAT-P-3b transit captured with a 90mm Triplet. 

Calibrated in PixInsight and Multi-Aperture photometry completed in AstroImageJ.

Outliers removed and used transit fit to clean the curve.

Sent in to Exoplanet Transit Database

TS Optics TS Photoline 90mm f6,6 Triplet FPL53 Apo CF 
ZWO ASI 1600MM Pro 
Skywatcher HEQ5 Pro (belt mod.) 
ZWO R 31mm 

113x90"

Gear:

Scope - TS-Optics 90mm CF Triplet

Camera - ZWO ASI1600MM-Pro

Mount - Skywatcher HEQ5 PRO (belt modded)

Guide scope - 9x50mm Finderscope

Guide camera - QHY5L-II Mono

Accessory - TS-Optics Photoline 0.79x Reducer

-----------------------------------------------------------------------

Acquisition:

L: 420 x 30" @ 0 Gain 10 Offset

RGB: 90x60" @ 76 Gain 15 Offset

50 Darks for each exposure time, 25 flats for each filter, 25 dark flats for each filter

Captured from Derbyshire, UK (Bortle 5 zone)

Probably one of my best renditions of M45 but could do with some more RGB data

CS,

Matt

2 hours ago, Gunshy said:

Actually no, the video isn't really a one off.   For the video, I didn't know what the subject matter of the video really was until it was stretched.

However, as I am playing with the script I am learning things myself, so I would like to modify my instructions somewhat, to : Place SP somewhere within the histogram near the peak,  move the peak up and test via the preview.   Then adjust to taste, keeping SP within the histogram range that is above "0" in the linear view.  

Here are my refined guidelines, but please realize that most of the people I have seen replying and reading these posts are far more skilled and talented than I at actual imaging and image processing than I am.   I am fearful that those just starting out will take my advice as gospel, when that is not my intent.   All of these stretches are reversible (via undo, image deletion, or the "undo" button), so the best advice I can give is to play with it, see what you like best, and make that your individual style of data interpretation:

The further left you put SP for the initial stretch, the more you will bring out the background.   However, if it is too far to the left, you may bring out low level noise too much.  Then try moving it towards the right.

If you put SP on the right hand side of the peak, then the background will tend to be left more dark.  So if this is your goal, ie leave. the background dark then it may be best to be on the RHS (Right Hand Side) of the peak.

As I say the video - in general the whole curve on the LHS of the histogram of the linear image - will generally contain the background noise, the background itself, and the subjected matter.   The histogram peak might be in the background or the subject matter and which of the two depends on the image, and how much you want to stretch it depends on what you want to show.   On an STF view, check how much of the image is covered by the subject matter itself.  If the subject matter covers more than half of the total image, the peak likely represents subject matter and you should place SP on the LHS of if.   If less than half, you can move SP more to the right.     

On the video a got a bit "lucky" on the SP position.   A little less lucky, and I would have had to go back, reposition SP, and conduct another initial stretch.   Clearly the peak in the Helix nebula image represented background.

Check the image after a "test" initial stretch and matching parts of the histrogram (including where the peak is) to the image will help you design a better initial stretch SP position as well as guide your follow-up stretches.   

Cheers,

Dave

 

 

I was wondering if it's possible to have some sort of realtime preview or is that not really possible for the script?

6 minutes ago, Gunshy said:

Thanks everyone for the kind comments.

Here is a half hour video tutorial on getting started with the GHS script.   It was taken from a Zoom meeting where I was showing some fellow members of my local centre (Victoria) of RASC how to get started.  I have put the video on Youtube.  Please excuse the videography and elementary editing.

https://youtu.be/ke5B8XQBwVc

I hope this helps.
Thanks,
Dave

The video provided is private, so no one can see it