Eta Carinae in H-Alpha

[montewilson]

Hi Guys - Here is a sum of 9x10mins in Ha of N-Car on the 4" Takahashi FSQ-106 and STL-11000m.

It needs a bit of work, but since Mike (IIS Sculptor) suggested I set the camera to -30deg not-20deg, my image quality has improved dramatically and my image noise has done a runner. Even better for future results, this is not perfect. The focus, polar alignment and a bad column all need looking at but I am really happy with the improvements from my normal output.

[h0ughy]

WOW those dark globule regions really stand out!

[Dennis]

Very nice work Monte – a stunner.:thumbsup:

I bet you enjoyed capturing this beautiful image so much more than sitting down for hours and hours trying to come up with some universal rules for the SPSP photo comp!:whistle:

Cheers

Dennis

[tornado33]

Very nice. Wheres the bad column? I cannot see it. Appently it can be mapped out anyway.
Scott

[montewilson]

You wont see it in this lo-res shot nor will you see the slight field rotation nor the soft focus but they are all there. As for the column, it is not as easy as it sounds. CCDSoft will get rid of it but leaves some artifacts that are visible when you stack nine shots. CCDStack has no feature I can see to get rid of it either. So I will probably have to get rid if it with PS. The column changes brightness from shot to shot so it can't reliably be removed with a dark subtract.

I am a bit puzzled because I paid for a Class 1 chip too!!

[tornado33]

Thanks for that.
Yep PS is handy for removing blemishes anyway :)
Scott

[leon]

Wow, that is some imaging, fantastic, I just love the H-Alpha imaging, well done.

Leon

[Peter Ward]

All the hallmarks of a great shot :thumbsup:.....only comment I can make is a bit more image scale would be nice ....as I suspect there is a of detail there...just can't make it out at that scale.

You may well have a hot column (could be just a hot pixel too), and given the price difference between C1 and C2 STL11k's I'd sure be badgering the dealer!

[strongmanmike]

Yes Ha only shots look pretty cool to me, always remind me of the good'ol Kodak Tech Pan 2415 B&W film shots of nebulae using red 25A filters, only sharper!

This shot looks great Monte and I imagine greater at full resolution, even with the slightly under par factors you mention? I would kill for an FSQ :wink2:

I have found running my FLI PL11002 camera (same chip as your STL) at -35C my subs are very smooth too (even at the 1.5sec full frame bin 1X1 download speed). Luckily the FLI can cool to 60C below ambient so I can run at -35C year round (without water, hoses and buckets) :D

Mike

[montewilson]

Hi Mike - If you are thinking of killing me for my FSQ tell me first and I'll just give it to you ha ha.........

You've been a bit quiet on the forum lately. I guess it must be those fantastically dark New Castle suburban skies

I will post a bigger version of the shot soon. I loved the old 2415 days. There was something romantic about film that zeros and ones just don't have. I guess these days numbers like 2415 and Super HG400 are like special code for astro old timers that we can use to identify each other.

Will you be coming to the SPSP? If you do, set up at the house where will have our imaging area, generators, monitors et al are all OK there.

[montewilson]

Here are some full-res sections of the shot. It is a brave man who will show his shots like this so here goes. The seeing was not good but some of the softness is because I didn't refocus during the imaging run. Naughty lazy boy!

I should have been a bit closer to the pole too. I was about 9' away from it and it shows. Later in the moring after adjusting the mount I did a new Automapper run and was less than 1' but by then the morning was starting and the next night was cloudy.

See the small planetary nebula in the top left of section2 ?

I don't know its name but it is too bright to not be listed somewhere. Any ideas?

Please be kind and enjoy it as it is, I will do a better one soon.

[Peter Ward]

Yep, H-Alpha produces needle like stars at that FL. Good effort just the same :thumbsup:

Can hardly wait to try my NewQ...but I suppose it would help if I actually picked it up from a mates place in Los Angeles. :doh:

[marc4darkskies]

Nice Monte! :thumbsup: Can't wait to give my new Ha filter a go.

Cheers, Marcus

[Ric]

Top image Monte, very sharp and detailed.

Cheers

[beren]

: up: Fine image Monte

[Karlsson]

To me this is quite impressive as it is :thumbsup:

Re. the planetary - tricky one, but my money would be on Hf39, aka Perek-Kohoutek 288-0.1, or PNG288.9-00.8...

[jase]

Pleasing to see you at it again Monte. The image presents a pleasing depth and awe about it. The higher resolution image shows lovely details which you've brought out well. Perhaps the background (black point) could be raised a little more without compromising the faint regions of nebulosity. Worth a try. It would make the image certainly more "contrasty". Well done.

[montewilson]

Thanks Karlsson - I'll try these numbers in Simbad.

Jase - Very kind and constructive as usual. What FWHM do you normally get with your images. It seems I am getting about 4", this image, for reasons not clear to me at the moment hovered around 7". I got a trial copy of CCDInspector to help me evaluate my focusing better.

[montewilson]

It was HF39 here is the picture. Thanks Karlsson.

[jase]

Based on my imaging run logs (below) ~6" appears the norm. I do get different values with the Ha filter. Also varies depending on the sky conditions.

14:22:02 Plate-solve pointing image.
14:22:03 3973 image stars found
14:22:04 1125 catalog stars found
14:22:04 Solved! 227 stars matched.
14:22:04 Average residual is 0.45 arcsec.
14:22:04 Pointing error is 2.348 arcmin @ angle 13.71
14:22:04 Image FWHM is 6.1 arcsec (1.74 pixels)
14:22:04 True focal length is 53.2 cm.
14:22:04 True image center (J2000): 10h 37m 46.8s -61 45' 59.61"
14:22:04 Imager sky position angle is 243.1 deg.
14:22:04 Image FWHM is 6.1 arcsec (1.74 pixels)
14:22:06 [sync] pointing model updated
....
14:39:37 Plate-solve final image
14:39:51 56891 image stars found
14:39:53 17099 catalog stars found
14:39:58 Solved! 305 stars matched.
14:39:58 Average residual is 1.13 arcsec.
14:39:58 Pointing error is 0.146 arcmin @ angle 33.13
14:39:58 Image FWHM is 9.0 arcsec (2.59 pixels)
14:39:58 True focal length is 53.2 cm.
14:39:58 True image center (J2000): 10h 37m 42.8s -61 48' 09.15"
14:39:58 Imager sky position angle is 243.1 deg.
14:39:58 Image FWHM is 9.0 arcsec (2.59 pixels)
14:39:58 (avg FWHM = 6.81 arcsec)
....
14:58:35 Plate-solve final image
14:58:50 56994 image stars found
14:58:51 17099 catalog stars found
14:58:55 Solved! 306 stars matched.
14:58:55 Average residual is 0.72 arcsec.
14:58:55 Pointing error is 0.110 arcmin @ angle 14.48
14:58:55 Image FWHM is 9.1 arcsec (2.62 pixels)
14:58:55 True focal length is 53.2 cm.
14:58:55 True image center (J2000): 10h 37m 42.3s -61 48' 10.13"
14:58:55 Imager sky position angle is 243.1 deg.
14:58:55 Image FWHM is 9.1 arcsec (2.62 pixels)
14:58:55 (avg FWHM = 7.58 arcsec)
....
15:02:02 Plate-solve pointing image.
15:02:03 2655 image stars found
15:02:03 567 catalog stars found
15:02:04 Solved! 176 stars matched.
15:02:04 Average residual is 0.34 arcsec.
15:02:04 Pointing error is 3.257 arcmin @ angle 349.98
15:02:04 Image FWHM is 5.4 arcsec (1.56 pixels)
15:02:04 True focal length is 53.2 cm.
15:02:04 True image center (J2000): 10h 49m 49.8s -64 45' 22.46"
15:02:04 Imager sky position angle is 243.2 deg.
15:02:04 Image FWHM is 5.4 arcsec (1.56 pixels)
15:02:06 [sync] pointing model updated
....
15:19:03 Plate-solve final image
15:19:17 65919 image stars found
15:19:18 8728 catalog stars found
15:19:20 Solved! 345 stars matched.
15:19:20 Average residual is 0.59 arcsec.
15:19:20 Pointing error is 0.120 arcmin @ angle 320.35
15:19:20 (pointing corrector updated with this observation)
15:19:20 Image FWHM is 8.4 arcsec (2.41 pixels)
15:19:20 True focal length is 53.2 cm.
15:19:20 True image center (J2000): 10h 49m 54.4s -64 48' 29.35"
15:19:20 Imager sky position angle is 243.2 deg.
15:19:20 Image FWHM is 8.4 arcsec (2.41 pixels)
15:19:20 (avg FWHM = 6.18 arcsec)
....
15:35:51 Plate-solve final image
15:36:05 66317 image stars found
15:36:06 8728 catalog stars found
15:36:08 Solved! 348 stars matched.
15:36:08 Average residual is 0.6 arcsec.
15:36:08 Pointing error is 0.130 arcmin @ angle 311.45
15:36:08 Image FWHM is 7.3 arcsec (2.08 pixels)
15:36:08 True focal length is 53.2 cm.
15:36:08 True image center (J2000): 10h 49m 54.2s -64 48' 29.73"
15:36:08 Imager sky position angle is 243.2 deg.
15:36:08 Image FWHM is 7.3 arcsec (2.08 pixels)
15:36:08 (avg FWHM = 6.64 arcsec)
....
15:52:42 Plate-solve final image
15:52:56 65301 image stars found
15:52:57 8728 catalog stars found
15:52:59 Solved! 349 stars matched.
15:52:59 Average residual is 0.58 arcsec.
15:52:59 Pointing error is 0.108 arcmin @ angle 326.74
15:52:59 Image FWHM is 8.6 arcsec (2.48 pixels)
15:52:59 True focal length is 53.2 cm.
15:52:59 True image center (J2000): 10h 49m 54.6s -64 48' 29.48"
15:52:59 Imager sky position angle is 243.2 deg.
15:52:59 Image FWHM is 8.6 arcsec (2.48 pixels)
15:52:59 (avg FWHM = 7.43 arcsec)
....
15:57:05 Updating pointing...
15:57:07 (taking 10 sec. exposure, Clear filter, binning = 1)
15:57:40 Plate-solve pointing image.
15:57:41 2879 image stars found
15:57:41 658 catalog stars found
15:57:42 Solved! 218 stars matched.
15:57:42 Average residual is 0.37 arcsec.
15:57:42 Pointing error is 5.777 arcmin @ angle 311.70
15:57:42 Image FWHM is 5.5 arcsec (1.58 pixels)
15:57:42 True focal length is 53.2 cm.
15:57:42 True image center (J2000): 11h 07m 43.0s -63 40' 52.25"
15:57:42 Imager sky position angle is 243.2 deg.
15:57:42 Image FWHM is 5.5 arcsec (1.58 pixels)
15:57:44 [sync] pointing model updated

[strongmanmike]

OK...I "will" kill you!...now, post 1 X FSQ106 to Acer Terrace Thornton NSW 2322 :D

Yes quiet I know, only done one image in 4 months :sadeyes:

Film huh? Lots of stories about using that stuff all soooo fond and romantic now (except for Joe) :)

I will most likely be at SPSP this year but as usual I will likely not bring my imaging gear. I like to treat SPSP as a bit of an astro holiday and get around and see and talk to lots of people and look through telescopes (and eat lots of donnuts) rather than get bogged down concentrating on imaging with my own gear and all the inevitable trials and tribulations operating a complex imaging setup tends to endure in unfamiliar surrounds. I did it one year and decided it just wasn't worth the trouble (although I scored my first SPSP astro imaging award that year with an image I took the morning of the competiton :D). I will undoubtedly come over for a sticky at the house though and say high :thumbsup:

Cheers

Mike

[robgreaves]

Hi Monte

Excellent shot :)

Regarding the noise, it's an interesting issue. Strictly speaking, with a dark frame removal, if done properly, it doesn't really matter what temperature you run at or how much noise there is in the raw .fits since a good master dark frame should (at least mathematically speaking) remove it. Even SBIG themselves recommend only a figure of 'x' degrees below ambient (not an actual specified set temperature), based on 75% or so cooler power/ efficiency figures. This, in reality, can translate to 'only' -7'C or -8'C on a balmy night. All this is in the CCDSoft manual somewhere.

However... running at a lower temperature again (assuming the cooler can handle the increased demand - it's not unknown for Peltier coolers to go pop!!) is very beneficial in that when you do your darks you are asking less of their performance and accuracy, if that makes sense, as you are having to remove less inherent thermal noise. OOI, to get to lower temperatures, I usually create a setpoint of say -15C, let it stabilise and let cooler power come down, then go to -20'C, stabilise, then -25'C where I then usually image. To go any lower I'd think about getting the 12V pump and a bucket of water out, especially in an Australian summer.

The key is getting a good master dark, from darks taken on the night on the same camera bootup sequence - not 2 weeks later..! 15 or more darks with a good median or Sigma reject combine usually work well. Also, if the sky looks good and you have time, darks in between light frames is good practice. If you end up with only a few dark rogue speckles in the final calibrated image from an 11MP sensor, you're definitely onto a winner and they're easily dealt with.

See you Wednesday.

Cheers - Rob