17 replies to this topic

[james7ca]

Captured just before (or actually into) astronomical dawn under red/orange zone light pollution on April 16, 2020 using a Celestron C6 and an uncooled QHY5III-178C camera (gain 30, offset 8, in SharpCap). This was taken at the end of a full night of imaging and I just wanted to take a "quick" shot to see how the Ring Nebula looked as dawn began. I was using unguided imaging on a Mach1GTO mount with a base exposure of 5 seconds and thus this is a stack of 180 frames producing 15 minutes of total integration time (180 x 5s = 900s = 15 minutes).

 

This just goes to show how bright of an object the Ring Nebula is even at f/10. I was also pleased with the resolution and I must have had pretty good seeing conditions because I was able to capture the Ring Nebula's double-double star that is below the nebula at about the seven o'clock position. I've also included a 1X scale crop showing those four stars with the faintest pair having a separation that may be only 1.3 arc seconds. This is only the second time that I've been able to clearly resolve the faintest pair and on my previous success I was using a 9.25" EdgeHD with a cooled, monochrome ASI178MM camera.

 

For more information on the double-double you can reference this post on CN that I made a few years ago (with more images):

 

  https://www.cloudyni...dpost&p=9429723

 

Interestingly enough, the FWHM on this image is kind of "crazy" at a measured 1.27 arc seconds, but I've checked the measurement several time using both PI's FWHMEccentricity script and PI's DynamicPSF tools (depending upon the model and the sensitivity I get measurements that remain consistent with that value). I'm pretty sure this is a record for me when using a one-shot-color camera (for a DSO), but note that the original image scale is just 0.3 arc seconds per pixel (plate solved, with the 2.4um pixels on the 178C). The larger image below is cropped and reduced in size to conform to the CN posting guidelines.

 

Image capture with SharpCap, image processing with PixInsight and Photoshop CC2019.

 

C&C welcomed as well as any previous references to the Ring Nebula's double-double star (have you ever resolved this feature?).

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Edited by james7ca, 18 April 2020 - 02:47 AM.

[clusterbuster]

Very nice !

 Mark

[Chen Sir]

wonderful!!!

your image makes me believe that my C8 also can photograph deep sky.

[siriusandthepup]

Super sharp and tiny stars! You should be proud of that shot.

[james7ca]

Mark, Chen Sir, and Ed, thanks for the notice.

 

There is another double star in this field that probably deserves some notice. It's Popovic 192 with a separation of 2.6 arc seconds and component magnitudes of 11.8 and 12.2. From the image it looks like these two stars have contrasting colors, one yellow the other blue.

 

To help identify Popovic 192 and my double-double I've attached a version of my image with labels for these two star systems.

 

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[c2m2t]

Hi All!

After a bit of back and forth, James has asked me to attach the following images. This compact delicate group of stars, 2 brighter + 2 dimmer is the case in question. The 2 brighter stars are the AB pair while the question posed is...what are these 2 other dim stars? Because, they are not included as part of HL 9001 or do not have a separate designation/entry in the WDS, they must be considered as only optical acquaintances to HL 9001 at this time...until someone in the future provides analysis to the contrary and prepares a report to a recognized Journal such as the JDSO, Journal of Double Star Observations. Once reviewed by the USNO staff and accepted, this pair will be added to HL 9001 or receive their own new designation bear the name of the new discoverer.

 

Cheers, Chris.

 

P.S. Upper image is a rotated screen capture from Stelle Doppie. The lower image is a rotated image of the M 57 region from Aladin to match James' colour image of M 57 which is to the right.

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[MeteorBoy]

Hi James,

 

That's a wonderful image of an old favorite.

 

Here's mine.  3 secs x 66 exposures for a total of 3.3 minutes.  This too was at F10 using a 20cm SCT.  Your double-double is better than mine.

 

[james7ca]

Just to clarify on what Chris posted (#6), the stars labeled as A, B, and C are those that are traditionally listed as being the multiple star system HL9001. However, Chris has noted that component "C" is no longer considered a physically bound member to the stars "A" and "B" (and those may also be in doubt).

 

So, the issue is the fainter pair (which I'll refer to as DE) that is located quite close to star "A." In fact, Chris has found (via data from Gaia, the satellite space observatory) that there is actually a third star even closer to one of DE stars (and about one magnitude fainter). So, this may actually be a double-triple (five stars rather than just four). Whether this is an optical pairing or a true physically bound system is currently unknown.

 

I've found Hubble images of the Ring Nebula that just begin to show the fainter member of this apparent triple and judging from that image I think its separation from DE is on the order of 0.5 arc seconds.

 

So, we may have a challenge here in that has any amateur managed to image this third star? It's going to require very good seeing conditions with a fairly large scope and a low enough exposure to not "blow out" components DE.

 

As for DE, I think I can detect slight colors to both of those stars. One appears yellow/white (similar to "A") and the other blue. If the blue coloring is real (and not a processing or imaging artifact) then I think that could lead to arguments that "A" and DE are not physically bound as that coloring might be more difficult to accept in terms of stellar evolution (since blue stars are typically more massive and brighter than yellow stars).

Edited by james7ca, 20 April 2020 - 12:31 AM.

[stf8]

Hi all,

Thanks to james7ca, I made a screenshot below of the hubble image of M57, with the E star of HL9001.

The resolution of hubble space telescope is below 0.1"arcsec (wikipedia), may be close to 0,05" arcsec/p (0

058). I made this estimation based on a comparison of one of my picture of Messier 3 and a photo from hubble space telescope (Second part of the blog/sorry it's in french language)).

http://www.astrosurf...-respectivement

 

Clear sky

 

ClaudeS

 

Edited by stf8, 01 July 2020 - 02:23 PM.

[sunnyday]

very nice shot , thanks .

[Bill G.]

Nice shot!!

This is my next target. I've shot it before with a C8 and a web cam. It came out OK but had some star trailing that I hope to avoid this time.

This time with a C8, QHY247C, and 2.5x barlow (maybe).

You've set the bar to measure by.

Thanks.

Bill G.

[freestar8n]

Nice work.  Had you used "optimally" sized pixels - they would have been too big to capture this detail.

 

The 6" sct has fwhm around 0.7" in the visible - so you are still comfortably above diffraction at 1.3" - but your seeing and focus still need to be very good for 5s.

 

Frank

[james7ca]

ClaudeS, thanks for the post of the Hubble image.

 

Sunnyday, Bill, and Frank, thanks for the notice.

 

With the full moon I'm back at trying to get a higher resolution image of the Ring Nebula. Last night I used my C6 after I got some pretty good images of the moon, Jupiter, and Saturn. Tonight (if the clouds hold off -- they look kind of threatening) I'm going to use my 9.25" EdgeHD.

[schmeah]

Excellent James! I love when things are found in the field of a rather common target that generate this kind of interest and discussion. I’ve always wondered about the optics and collimation of my 9.25 Edge as well as my local seeing conditions. This would be a good test. I haven’t shot this target since my earliest days of imaging back in 2007. You’ve encouraged me to give it another shot.

 

Derek

[stf8]

Hi james7ca,

 

Yes, it not so easy to make a picture of this double double. I tried tree times and succed at the end with my 6 inches APM LZOS refractor 1200mm. Barlow televue 2X and ASI ZWO 290MM. 500 pics of 2s.

http://www.astrosurf...à-03-darcpixel/

 

 

With à better constrast with registax 6

 

ClaudeS

[james7ca]

ClaudeS, that's a really good image and thanks for your continued contributions to this thread. You did better than I could even with my 9.25" EdgeHD.

[stf8]

For sure james7ca, you have a very good Celestron 6 inches.... don't sell it...it's a rocket....

[RogeZ]

Sorry to resurrect old thread but I have to try this

What a cute little star system…