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Optical outburst of the quasar CTA 102

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#101 Aquarellia

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Posted 29 December 2016 - 03:33 PM

 

./..

When I defocus stars to help to estimate their apparent brightness, their color is somewhat revealed as a pastel shade. Defocused, CTA102 appears pretty neutral and, if anything, duskier than blue.  Have you noticed if there is a tint to this quasar?

--------

C

I was looking for an eventual coloration but no color was yet detected from my refractor.

I was wondering to detect some red color because of the speed of this object (30'000 km/s) but I'm maybe wrong with the redshift effect linked with the general observed color.

Michel



#102 Tom Polakis

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Posted 29 December 2016 - 10:14 PM

Brian Skiff is not prone to performing visual observing stunts, but tonight he viewed the quasar in his 70mm Pronto.  I pointed out that this may be the distance-vs-aperture record, but he encourages people to give it a try with even smaller telescopes.  Here's his report.  My scope is indeed acquiring images at this moment, through 4h UT, after which it will be too low.

 

 

I have just come in from picking up the field
and the blazar using my 70 mm Pronto the the Lowell
Anderson Mesa site (2016 Dec 30, about 2h UT).
This was right at the end of astronomical twilight,
and as I write this a bit later my SQM meter reads
21.47 for the sky brightness.  The zodiacal light
and Venus very bright in the southwest of course,
with the blazar right on the edge of the obvious
part of the ZL.
     I identified the blazar securely using 95x
(4.8mm Nagler), but did so more comfortably at 75x,
then finally just 30x (15mm Panoptic).  Given my being
years out of practice with star-hopping and visual
observing generally, it was faint but not difficult.
     I used the nearby star TYC 1154-0373-1 to the
east as a reference (V=11.75 in APASS DR9 and
V=11.70 in the ASAS-3 database), I'd call it a
but fainter than that, perhaps 12.2. 
     Tom Polakis may be getting CCD images nearly
contemporaneously (I used a printout of one of his
earlier V-band images to do the final star-hop),
and if so tomorrow I can measure them and give you
an answer good to < 0.01 mag.
     Anyway, as Tom P suggested this must be some
kind of distance-versus-aperture record (someone
ought to try a smaller aperture).  But now when
some little kid asks how far I can see with this
telescope, I can say 8 billion light-years.


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#103 stevecoe

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Posted 29 December 2016 - 11:44 PM

Hi Tom, Brian, et al;

 

I set up the 9.25 SCT in the RV park near Wickenburg, Az.  Once it got good and dark I used to GOTO to find NGC 7305 and then the blazar.  It was obvious at 100X and I would estimate 11.6 magnitude.  I am not very good at magnitude determination, so don't count my "guesstimate" as coming from a knowledgeable source.  I do look forward to Brian's calculation.  It is certainly fun to view something 7.7 billion light years distant.  That is easily my furthest object observed.

 

Clear skies to us all;

Steve Coe



#104 Dave Mitsky

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Posted 30 December 2016 - 12:35 AM

Sasa reported seeing CTA 102 through a 63mm Zeiss Telementor on December 2nd (post #22), December 16th (post #60), and December 29th (post #96).

Dave Mitsky



#105 Sasa

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Posted 30 December 2016 - 01:36 AM

The blazar was so bright last night in Telementor that it would be possible to spot it in 50mm telescope and probably even in smaller ones. This must be an extraordinary source indeed. I have one unfinished but functional OTA for 50/540mm lens. I may give it a try, this could be fun

Edited by Sasa, 30 December 2016 - 03:14 AM.

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#106 BKSo

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Posted 30 December 2016 - 03:18 AM

I tried to observe the quasar last night with my 4"sct under a red zone sky without suceed :bawling: I could not even identify the star field. The question is what kind of sky does it take to observe this target with a small telescope :confused:



#107 Sasa

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Posted 30 December 2016 - 04:01 AM

Nothing special. I was observing it from our light polluted backyard (5.0 mag sky) from small city just at the border of 1+ million people city. It took me about half an hour to locate the field in 110mm refractor when I was observing the quasar for the first time. The quasar was much fainter then (around 12.9 mag). High enough magnification and shielding the eyes are the two keys for reaching faint stars under light polluted skies.


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#108 andycknight

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Posted 30 December 2016 - 04:41 AM

BKSo, on 30 Dec 2016 - 08:18 AM, said:

I tried to observe the quasar last night with my 4"sct under a red zone sky without suceed :bawling: I could not even identify the star field. The question is what kind of sky does it take to observe this target with a small telescope :confused:

 "When bright" It should be an easy target in a 4" SCT, but unfortunately we have light pollution/haze etc...

 

I had a similar "impossible" challenge, when I first attempted it and the Mag 7.2 HD212989 signpost was impossible to find in my 8" SCT!! - All you can do is try another night and get away from city lights!

 

With regards to locating:- I started by copying the S&T finder chart and performing a mirror image and then rotated 180 degrees to make North the top, such that it exactly matched my SCT view through a diagonal. I also chose an eyepiece to give me a ~1 degree FOV (similar to the 1.2 x0.8 degree chart) so I had a good sense of scale.

 

As the wide S&T chart is not ideal to easily locate HD212989, I used 7x50 binoculars to familiarise myself with the area. I ran an old computer program (I like Skyglobe, but any will suffice) to help identify it's exact location.

 

The C5 (125mm  SCT) Telescope was now 'knowingly' pointed at HD212989 and then used to 'hop' to the correct area using the S&T detailed chart. I must confess, I did familiarise myself with the chart first. (Note only the brighter stars will be visible)

 

It soon became obvious, that a point of light did not belong there. I then looked for nearby patterns of stars to ensure I was observing the correct spot and hence confirmed I had identified the Quasar.

 

In my C90 (90mm Mak): Due to light pollution/haze, the Quasar was only occasionally visible using adverted vision. So I had concentrate my gaze to one side of where I suspected it to be. This places the star on a more sensitive part of the retina. It takes practice, but will often allow you to see a magnitude fainter.

 

Good Luck

 

Regards

 

Andy.


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#109 timokarhula

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Posted 30 December 2016 - 06:07 AM

 

Brian Skiff is not prone to performing visual observing stunts, but tonight he viewed the quasar in his 70mm Pronto.  I pointed out that this may be the distance-vs-aperture record, but he encourages people to give it a try with even smaller telescopes.

I wonder what the distance-vs-magnification record is?  Small telescopes with high magnification have better limiting magnitudes than binoculars with slightly larger aperture.  I saw CTA102 with 25x magnification (25x100 binoculars) on December 23 in mediocre conditions.  See my post #76.

 

/Timo Karhula



#110 Sasa

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Posted 30 December 2016 - 07:10 AM

I should be able to spot it in 25mm at 11.0 visual magnitude from our backyard if the conditions are good enough. This is just downscaling the 13.0 magnitude I can reach in 63mm. It is truly spectacular object.

#111 Sasa

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Posted 30 December 2016 - 12:10 PM

Just tried it with 50mm refractor (Zeiss E50/540). Quasar was definitely fainter than yesterday, I could hold with concentrated averted vision the two nearby V11.0 and 11.3 stars. Blazar was more dificult, in 6mm ortho (90x), I could hold it only for several seconds, the longest clearest view was for about 5 seconds. Hard to tell, how bright it was.
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#112 CatalinMT

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Posted 30 December 2016 - 12:58 PM

I just saw the quasar with a 90mm f/10 refractor at 50x & 91x this evening, it was easy. Estimated mag. ~ 11-11.5. Just for fun, I tried like Sasa with  50mm aperture(Borg ED) at 25x and was thougher and only visible with averted vision! :shocked:


Edited by CatalinMT, 30 December 2016 - 01:03 PM.

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#113 Aquarellia

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Posted 30 December 2016 - 01:35 PM

I just post on AAVSO my 3 estimations for the begining of this evening : all more or less 11.5, refractor 6" f8, magnifications 40x to 150x.  After dinner I'll try with a 5" bino and a 3" bino. 

By the way Ss Cyg is probably going up.

Michel


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#114 Tom Polakis

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Posted 30 December 2016 - 02:24 PM

The magnitude estimates between 11.5 and 12 sound about right.  I took seven images through a V filter in a period just shy of 2 1/2 hours, and Brian Skiff reduced the data.  This plot shows very short term changes in the brightness of the quasar.

 

Tom

 

G68JNE4.jpg


Edited by Tom Polakis, 30 December 2016 - 02:28 PM.

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#115 Aquarellia

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Posted 30 December 2016 - 02:44 PM

I just post on AAVSO my 3 estimations for the begining of this evening : all more or less 11.5, refractor 6" f8, magnifications 40x to 150x.  After dinner I'll try with a 5" bino and a 3" bino. 

By the way Ss Cyg is probably going up.

Michel

Well 1" makes the difference, I can only detect the quasar from time to time, and only with averted vision with my bino Vixen 5" with 40x ep, so I don't test the 3" ofcourse.  I can only say better or equal to 11.7

Michel


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#116 BrooksObs

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Posted 30 December 2016 - 10:21 PM

I caught CTA 102 at magnitude 11.6 this evening (December 31.00UT) using the AAVSO's 11.0 ad 11.7 comparison stars. This indicates that the blazar's decline from the peak of its latest flaring, occurring very near December 29.7UT, continues. In addition, I noted the presence of the 18 hour old moon in late twilight very low in the southwestern sky this evening, heralding its soon to begin growing interference with further observations of CTA 102 over the next 15 or 16 nights.  

 

BrooksObs


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#117 Organic Astrochemist

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Posted 31 December 2016 - 02:33 AM

The magnitude estimates between 11.5 and 12 sound about right.  I took seven images through a V filter in a period just shy of 2 1/2 hours, and Brian Skiff reduced the data.  This plot shows very short term changes in the brightness of the quasar.

 

Tom

 

G68JNE4.jpg

It blows my mind to think that some of this rapid variability may be caused by plasma in the blazar's jet moving near the speed of light. As a result, we observe variations over a shorter time than they occurred at the source. Time is not absolute, but relative. What an illustration of general relativity. An explanation is given here

Optical View of BL Lacertae objects


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#118 goodricke1

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Posted 31 December 2016 - 05:30 PM

I noted the presence of the 18 hour old moon in late twilight very low in the southwestern sky this evening

Not being picky but the moon was app. 40 hours old at that point.



#119 swetzel

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Posted 01 January 2017 - 09:43 AM

So what is the best time to view this thing?



#120 Aquarellia

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Posted 01 January 2017 - 09:54 AM

So what is the best time to view this thing?

Directly when the sky is dark, +/- one hour after the sunset so this object will still be high in the sky.  Tonight is better than tomorrow because of the increasing moonlight.

Yesterday evening its magnitude was 12.0

Good observation !

Michel


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#121 CatalinMT

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Posted 02 January 2017 - 02:25 PM

I observed the quasar on Dec. 31st 2016 and Jan. 1st 2017 again. On Dec. 31st it was dimmer than on 30th, around mag. ~12 an visible mostly with averted vision. On Jan. 1st it was not visible at all. All observation made with a 90mm refractor at 91x. I attach a small sketch with its variability.

 

Attached Thumbnails

  • CTA102.jpg

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#122 Aquarellia

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Posted 02 January 2017 - 02:51 PM

That's a superb set of observation of this phenomenon!!!  Nice sketches and interesting evolution.

A big bravo Catalin!

Michel



#123 BrooksObs

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Posted 02 January 2017 - 03:19 PM

I observed the quasar on Dec. 31st 2016 and Jan. 1st 2017 again. On Dec. 31st it was dimmer than on 30th, around mag. ~12 an visible mostly with averted vision. On Jan. 1st it was not visible at all. All observation made with a 90mm refractor at 91x. I attach a small sketch with its variability

 

Indeed, it would appear that CTA 102 is taking a big dip in brightness following the peak of its latest flare. Some observations from last evening are putting it as faint as magnitude 13.2 and still fading. Will this latest event signal the end of this series of flarings...or herald an even more extreme brightness flare coming in the next few day? Talk about a bizarre object! :wink: 

 

BrooksObs


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#124 Nobile2HD

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Posted 02 January 2017 - 05:17 PM

Well that explains my view of this object this evening. It was my first view of his through my 12" SCT; averted vision was needed when using the 30mm ep and I could just about see it with direct vision with the 24mm. Thought something was amiss when I read reports of people seeing this through significantly smaller apertures!



#125 nytecam

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Posted 02 January 2017 - 06:00 PM

Did think of stopping down my scope to 20mm aperture but instead took a 1sec shot at full aperture as below.  Even 1/10s exp recorded it but so what !   The blazer ~m12.8 tonight so well down on a few days ago.

 

Nytecam

Attached Thumbnails

  • cta102q170102x1smgx.jpg

Edited by nytecam, 02 January 2017 - 06:10 PM.

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