a few gras images

[monoxide]

hi guys,
heres a few images i took using the G13 trial.
remote imaging is pretty fun

[jase (Jason)]

Good work Tony. Pleased you liked the remote imaging experience. Images are a little noisy, but show promise. Well done.

EDIT: Are you apply darks and bias frames from their calibration library? All the images appear to have a glow down the right side.

[monoxide]

thanks Jase,
you can only do so much with single (uncalibrated?) subs but it was a good experience getting some data without having to do battle with my equipment in the back yard.

for what it is GRAS13 works well, mabee not so good on fainter targets as you only get a low res jpeg sent to you that wouldn't be that great for stacking but it seems to do ok on the brighter subjects

edit: Jase, i checked for the calibration files but couldn't find any for G13 since its new and still in testing i guess.

[Aussie Pete]

Evening gents,

Nice Mono

Its early days and the scope is performing like a little beauty, although just to clear things up, technically speaking G13 delivers a single shot color FITS file to the obs puter, which is rapidly calibrated with bias, darks and flats calibrations frames. The image is then digital dynamically (DDP) stretch processed to 800x600 jpeg image ready to be delivered to the owner.

Thank you for the kind words.

Pete

[monoxide]

Hi Pete,
thanks for clearing that up, ill drop you a pm in a minute.

i should have mentioned:
NGC3324 is a stack of 3x5 min subs
NGC3372 and IC4605 are single 10 min subs
NGC2997 is a single 5 min sub

[jase (Jason)]

Originally Posted by Aussie Pete

The image is then digital dynamically (DDP) stretch processed to 800x600 jpeg image ready to be delivered to the owner.

Thank you for the kind words.

Pete

Pete, how do you automate the DDP stretch so the curve is optimal for each image/target? An auto background and mid-level tends to result in black clipping - far from optimal. Does the DDP also sharpen the image in the process (MaximDL default)?

[Aussie Pete]

Hi Jase,

Well...for that kinda peek at the guts your better of sending Brad an email. He has already posted in an adjacent thread here, that he is more than pleased to offer illumination in that regard.

But we should not forget that this telescope will have a mission and it will not generally involve high end or gooroo users when fully commissioned Jase. Its an entry level imaging machine.

The kind of image control your mentioning is better done on one of the other gras scopes in FITs format and thus beyond the many curious 'arm chair' astronomers . Beyond the 'scope' of this system test.

Ta mate and clears skies..

Pete

[jase (Jason)]

No problems Pete.

Cheers

[Brad Moore]

Hi Jase,

G13 has been designed for people to get their feet wet without all the complexity of understanding how to process images. The design goal of G13 is, simple, fun, one click image, delivered via email. This is a beginners to intermediate system not a system that someone yourself might find interesting long term. By design compromises exist on G13 Let me explain.

The image glow you are referring to is caused by the moon. We are evaluating the performance and may take it offline during the full moon.

The calibration process is automatic a bias scaled dark is applied and a flat.

The DDP is applied via a script and I try and set the points based on the histogram, however it doesn't always get it right but close enough for this system, clipping will exist nothing I can do about it in a automated system. This DDP doesn't sharpen the image.

Noise. This is a 10 min image 3:3:3 RGB shot at 1600x1200 on a 90mm refractor with a low QE CCD. To deal with the noise I reduce the image to 800x600 otherwise I would need to have exposure times of 30+ mins if not longer to keep the noise levels the same at full resolution. If I offered the 10 min full resolution image would be much less pleasing than the 800x600 image, because as you know reducing a image in size is a great way to deal with noise. Due to the signal to noise being so low when I JPEG compress the image it causes some graininess to it but no real more than in its raw format.

I then convert the image to a JPEG with a slight compression and delivery it via email. JPEG was choice as large portion of the users don't understand what a FITS or TIFF file is or how to correctly work with it, little alone click on the attachment and open it up in one click from the email. The ones that do they are more than welcome to trial whole GRAS network which includes access the the FITS files.

Overall the results have been really good and the feedback and been 95% positive.

Good to hear from you, hope things are going well for you.

Cheers,
Brad Moore

[jase (Jason)]

Hi Brad,
I'm fine, hope you are too.

Thanks for your response. This certainly adds clarification of the target audience. Pleasing to see you guys cater for all sorts. Not sure if you've thought about automatic noise controls post calibration such as scripting flatten background and/or Russ' anisotropic gaussian blur MaximDL console plug-in. While you'd very rarely apply noise reduction to an entire image, you may find for G13 purposes this would be acceptable if a mild pass is applied and background flattened. These may (or may not) improve the output of the images.

Good work on this initiative. The more people bitten by the imaging bug, the more interesting images we'll see around here and on other forums. Bugger, the ACP forums, I'll be coming your way for my support from now on. I'd say you'd be pretty close to scripting your own image automation engine by now. Shame CCDAutoPilot users still don't have a web interface. Not sure what John Smith is thinking...thin clients like VNC or TSclient don't like high latency comms...anyway enough of my bantering, better get back to work. Catch you around.

Sorry Mono, didn't mean to hijack your thread. I'll retreat into the shadows while continually assessing the scene.

[Ric]

Hi Tj, great looking images, remote imaging sure looks intriguing, I'll have to wait until I get broadband though.

Cheers

[monoxide]

thanks Ric, although i didn't really do much but point and click.

ill definately be checking out some of the other scopes though.
especially when i get my new guide and focus setup going, it will be interesting to combine GRAS data with my own.