Help in identifying a (new?) comet in Sagittarius…

[Dennis]

Hello,

Tonight, August 8th 2008, whilst taking a photo of the Hubble Space Telescope passing by Jupiter I noticed a faint blue object near the recorded trail of the HST. The FOV is approx 2 x 1.25 degrees.

Subsequently, I took several other photos of the object and it shows distinct movement as show in the attached composite image.

I have tried a quick search using my normal software and could not locate a current comet in this position.

Cheers

Dennis

[astroron]

Dennis it is Comet C/2007 N3 LULIN.
See my post
http://www.iceinspace.com.au/forum/showthread.php?t=34406
From last month
Regards :thumbsup:
Ron

[Dennis]

Hi Ron

Thanks for that. That particular one didn’t come up on my various searches and with it being such a bright object, I figured that the chances are it was an existing one, although my heart did skip a beat or two when I first spotted it!

Cheers

Dennis

[Lester]

Good capture Dennis.

[Dennis]

Hey Ron

I just plotted C/2007 N3 Lulin in The Sky and it is over 3 degrees away from where I have recorded it in the photos. Can there be this much of an error in reported positions?

Cheers

Dennis

[astroron]

Dennis , I don't know the field of your photo but my copy of THE SKY gives the seperation of the Comet
From Jupiter: as
Angular separation: 04°07'33"
Position angle: +293°28'
Is that what you get?
It is a very fast moving Comet.
When did you update the ephemerous for the comet?
Ron

[Dennis]

Hi Ron

I updated the comet data from the web after your post above. The centre of the field is at:

RA: 19h 01m and DEC: -22° 07’
Field of view is approx 3° x2°.

Cheers

Dennis

[Dennis]

Here is how it looks on The Sky for 8:00pm tonight (8th August 2008). Is that what you get?

Cheers

Dennis

[astroron]

Yes,I am at a loss to explain the anomaly:shrug:except maybe as it is close to the Zenith, could it be the shortening affect:shrug:
Or maybe there is another Comet that you may have Discovered:D
Ron

[AlexN]

geez its moving fast in the course of an hour....

The 400mm L makes for a nice wide field APO dennis, whack it on your EQ mount and get some deeper shots of your comet! :D

[Dennis]

Hi Ron

Thanks for your help – I’ll sleep on it and start the search afresh tomorrow. I should really have slewed to the plotted position of C2/2007 N3 Lulin in The Sky just to check if it was there, but I packed up a while ago.:doh:

Cheers

Dennis

[Dennis]

Thanks Alex – it was riding on the eq mount and I’ve collected a few 60 sec, 120 sec and 600 sec exposures. The light pollution looks ghastly on the raw frames!

Cheers

Dennis

[citivolus]

I can't help but wonder about an internal reflection, as it seems to be opposite Jupiter in all of your shots. However, the colour is very cometary, and the direction of motion seems consistent.

The calculated FOV for your configuration is 190x127 minutes. The approximate coordinates for the object at 21:03 are: 18h59m49s DE:-21°17'48"

Regards,
Eric

[citivolus]

One more interesting tidbit: C/2007 N3 Lulin is moving in the opposite apparent direction from this, away from Jupiter.

[Dennis]

Thanks Eric, I appreciate your help and comments. I did a very quick and dirty alignment of some of the sequences I captured last night and the path of the “comet” appears strongly curved and seems to “wander” rather than move in a straight line.

Along with what appeared to be 2 or 3 faint tails, this also led me to believe I may be looking at some optical artefact, pending a more high fidelity alignment and animation which I’ll try later.

Cheers

Dennis

[Dennis]

Okay. Here is an animation of 10 frames captured from 9:40pm to 10:19pm. Each frame is a 120 sec exposure with a 2min 20sec delay between captures to allow for In Camera Noise Reduction and download time.

The region has been cropped severely and levels stretched to reveal the “spiky” nature of this mystery object. Looking more like an optical system artefact based on its wandering and the radial spikes?

Cheers

Dennis

[theodog]

Bad luck Dennis.
But hey, didn't it give the heart and mind a workout for a while.

Good to see a systematic approach to solving the image. Good teamwork from IIS members too.:D
Keep at it -not all will be artifacts.:thumbsup:
Nice sharp stellar images.:)

[citivolus]

Pity, but at least you had some fun! Good practise for the next time around!

Regards,
Eric

[Dennis]

Thanks Jeff & Eric.

I’ll probably drive the final nail into the coffin of this “comet” by going out tonight to image the same region with the same set up and then rotate the 40D/400mm F5.6 lens combo 90° and 180° to see what turns up. Something I should have done last night with hindsight.

Cheers

Dennis

[Dennis]

Here is a crop from the full frame, of a histogram stretched 5 minute exposure revealing the true nature of this imposter! If the stars weren’t so tight, I’d return this lens, as I figured no Canon “L” lens should show signs of lens flare!:whistle::lol:

Cheers

Dennis

[jjjnettie]

Bad luck Dennis. But a nice capture just the same.
I might have a go at it myself tonight.

[Kal]

For an optical artefacty that sure does appear like a comet, the colour is almost perfect!

[Jen]

:eyepop: looks cool in the animation shots :thumbsup:

[AlexN]

my 70-200 suffers from flaring when pointed just off centre of the moon. Haven't tried it on jupiter though..

[5ash]

Heres a picture i took monday night using a g star on an lx90 .The first pic of M22 gives an idea of the field of view , the comet is dead centre in the second pic
regards philip

[astroron]

Dennis what concerned me but I didn't think to mention was the size of the object (comet) in your image:( Comet C/2007 N3 Lulin is only very small:sadeyes: and the object in your image was quite large:)
I also noted the flaring but thought you had taken that into account;)
I hope you can take an image of the True (Comet) tonight :)
Ron

[Dennis]

Dear colleagues

It is with deep regret that I announce the passing, into oblivion, of last night’s “comet discovery” in Sagittarius. Sadly, it was eventually proven that the “comet” was nothing more than the result of internal reflections in the Canon 400m F5.6 – a cosmic imposter initially rendered plausible by the realism inherent in the fuzziness and colours of the lens flare.

Here is a 2 Layer composite showing the (faint) position at 6:14pm in Frame 1 (10 secs) superimposed on Frame 2 (30 secs) taken at 8:15pm, clearly revealing the duplicitous nature of this non-cosmic interloper.

Lessons learned:

This was 1st (astronomy) light for the Canon 400mm F5.6 under these conditions.
When using a new optical system for the 1st time be on the look out for any optical or system artefacts, as you do not yet know how the system will behave under various lighting conditions.
If its too good to be true, it probably is!
If you find something similar, rotate the sensor 90 degrees or change the field slightly and take further exposures to see if the object moves.

Thank you Ron and Ric for your assistance in helping establish the true identity of this cosmic thief!

Cheers

Dennis