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Galactic Classical Nova in Canis Major

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#1 vakulenko_sergiy

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Posted 25 March 2018 - 05:47 PM

Spectroscopic Confirmation of TCP J07134590-2112330 as a Galactic Classical Nova in Canis Major.

TCP J07134590-2112330 was discovered by Yuji Nakamura on 2018 March 24.5 UT as a 12 mag optical transient.

 

J2000 position of TCP J07134590-2112330 is RA = 07h13m45.843s , Dec = -21d12'31.28"

Searching map:

TCP J07134590 2112330 Map

Source: http://www.astronome...org/?read=11475

 

Few hours ago I have observed nova, my estimate is 12.0, but it is not accurate, since I shot through the thee smile.gif

NovaCanisMaj L 03 25 220552 300sec 1x1  frame1 C

Edited by vakulenko_sergiy, 26 March 2018 - 05:19 PM.

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#2 Aquarellia

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Posted 26 March 2018 - 05:45 AM

My estimation is in line with yours, a little bit fainter than +11.5, the moon was not helpful

I was not yet able to post this estimation in the AAVSO DB, did you succeed ?

Michel



#3 BrooksObs

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Posted 26 March 2018 - 08:58 AM

A most unusual discovery! I can't recall ever hearing of a nova occurring in Canis Major in my lifetime and certainly not during the many decades of my association with the AAVSO. I will admit that there have been several in adjacent Monosceros over that period of time. Too bad the event has taken place so late in Canis Major's observing season as this would have a made great, even if perhaps relatively brief target. As it is, I might get a look at the nova tonight, but that will likely be my last opportunity before growing moonlight and trees to my southwest hide the object permanently.

 

BrooksObs



#4 goodricke1

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Posted 26 March 2018 - 09:42 AM

There was Nova CMa 1934, well before your lifetime wink.gif



#5 vakulenko_sergiy

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Posted 26 March 2018 - 10:25 AM

My estimation is in line with yours, a little bit fainter than +11.5, the moon was not helpful

I was not yet able to post this estimation in the AAVSO DB, did you succeed ?

Michel

Good to hear that.

I've not tried to submit my results to AAVSO because I'm newbie in photometry, I need to read some how to guides first.

I can share calibrates fits, if some who can submit my results.

 

Update1: I was wrong with 11.7 estimation (I've used incorrect catalog for reference stars). 1st post was updated.

 

Update2: Few hours ago observed nova again, my estimation of it's brightness ~ 11.6 (bit brighter from yesterday).


Edited by vakulenko_sergiy, 26 March 2018 - 05:23 PM.


#6 BrooksObs

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Posted 26 March 2018 - 10:44 PM

As I had hoped, I did get a look at the newly discovered nova in Canis Major this evening shortly after the conclusion of twilight.The unique arrangement of stars in the immediate field surrounding the nova made it easy to identify. Using the AAVSO's chart for the nova, as of March 27.06UT I made the nova to be a magnitude of 11.6 .

 

There was Nova CMa 1934, well before your lifetimewink.gif - goodricke1 

 

Indeed, that would have been just a little before my time!

 

BrooksObs


Edited by BrooksObs, 26 March 2018 - 10:51 PM.

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#7 BrooksObs

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Posted 27 March 2018 - 09:13 AM

I would note that the latest observation of the nova, posted to the AAVSO by Andy Pearce (a highly reliable southern observer) on March 27.52 UT, gives a magnitude of 11.0 . Taken together with the other admittedly limited observational data available so far suggests that the nova may still be in its ascending stage. A maximum of near magnitude 12.0 struck me right from the beginning as surprisingly faint for this galactic location, although I will not venture any guess just how much further the nova might rise before peaking. Taken at face value, this somewhat slow rise might be taken to also imply that Nova CMA 2018 may be a rather slow nova and will remain observable, particularly from the Southern Hemisphere for an extended duration and not of the "flash" type (Class Na).

 

BrooksObs



#8 BrooksObs

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Posted 28 March 2018 - 09:42 PM

The suspicion I had voiced in my post of yesterday that Nova CMA 2018 was still in the ascending stage has been proven correct by the latest reported observations. As of March 28.8UT the nova's magnitude had attained a magnitude of 10.3 and likely continues in ascent. Unless the pre-nova can be clearly identified, it is difficult to project just what magnitude the nova is likely to attain when it peaks. In addition, given that the ascent stage has so far occupied more than 5-6 days, perhaps significantly more, Nova CMA 2018 must almost certainly be a rather "slow" nova as I also speculated previously.

 

BrooksObs

.


Edited by BrooksObs, 28 March 2018 - 09:42 PM.

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#9 BrooksObs

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Posted 29 March 2018 - 01:48 PM

Looking over the data submitted to the AAVSO overnight, these appears to indicate that Nova CMA 2018 has plateaued at about magnitude 10.0 , the observations indicating little or no noticeable further brightening in the course of the past 24 hours.

 

However, just as an outside possibility this might not necessarily mark the peak of this nova's outburst. Some of us will recall last summer's Nova Sct 2017 which similarly displayed a well documented slow initial rise to a distinct plateau, only to seemingly re-ignite and rise a further two magnitudes after about a week spent at magnitude 10.7-10.8 . Now admittedly, chances of such a well defied event being replicated by another potentially slow nova in such rapid succession seems slim. Nevertheless, such a standstill, commonly referred to as a "pre-maximum halt" has be documented in the lightcurves of quite a number of past novae, but these events will of course be missed unless the nova is detected while still in the ascending stage. At the same time, the faster a nova's rise, the less time it seems to spend in this plateau stage. For Na class novae (the fastest type) it may be as brief as an hour, or two, while in the case of dramatically slower evolving Nc novae, it can occupy days.

 

BrooksObs


Edited by BrooksObs, 29 March 2018 - 01:52 PM.

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#10 BrooksObs

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Posted 31 March 2018 - 07:16 AM

Unfortunately, rather than perhaps exhibiting a pre-maximum halt in its light curve during the past couple of days, Nova CMA 2018 appears to have peaked at magnitude 10.2 on about March 29.00UT and is now in a slow decline which has brought it to nearly magnitude 11.0 by early this morning our time. It will now be interesting to following the nova as long as possible before it descends into the evening twilight to see if its decline will be a smooth one, or perhaps will display a series of violent brightness fluctuations as did slow nova Nova Sct 2017 many of us watched last summer and fall.

 

BrooksObs


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#11 Aquarellia

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Posted 31 March 2018 - 07:44 AM

Unfortunately, rather than perhaps exhibiting a pre-maximum halt in its light curve during the past couple of days, Nova CMA 2018 appears to have peaked at magnitude 10.2 on about March 29.00UT and is now in a slow decline which has brought it to nearly magnitude 11.0 by early this morning our time. It will now be interesting to following the nova as long as possible before it descends into the evening twilight to see if its decline will be a smooth one, or perhaps will display a series of violent brightness fluctuations as did slow nova Nova Sct 2017 many of us watched last summer and fall.

 

BrooksObs

Your right, and about this Nova Sct 2017 this star is still visible, I continue following it's light, the last estimated visual magnitude was around +12.0.  more than the discovering magnitude in July last year.

So ok for following this new one, as always for novae, we don't know what the curve will be.  This is an astronomical suspense!

Michel


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#12 NJScope

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Posted 31 March 2018 - 07:03 PM

My brightness estimates for N CMa 2018 from last evening (31Mar2018 @UTC=02:28) were B-mag 11.931 ±0.016, V-mag 10.645 ±0.005 and Ic-mag 9.297 ± 0.004).  Unfortunately this system is barely above the wall of the roll-off-roof observatory when its dark enough to image in AZ and probably won't get many more chances to collect data.  The B-, V- and Ic-magnitudes for N CMa 2018 (T) were estimated using the AAVSO values for the stars (1-5) identified in the accompanying image. N CMa 2018-0001_Green.PNG


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#13 freestar8n

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Posted 01 April 2018 - 03:29 AM

I'm well placed in Melbourne, Australia for this event - and luckily had some clear skies so I was able to image it in Sloan i' r' g' filters.

 

NovaCMa20180331s.jpg

 

The nova is the reddish star in the very center, with north up.

 

Imaged with EdgeHD11 at f/7 with multiple 30 second exposures on a cmos ASI1600 cooled camera.

 

A full res. version and more details are available at:  https://astrob.in/340021/0/

 

On March 31 at 10:00 UT I measure the Sloan magnitudes to be:

 

i' = 10.35, r' = 10.80, g' = 11.79 g'-r' = 0.94

 

Using the Jordi 2006 conversion formula, this maps to:

 

B = 12.30, V=11.24, R=10.72 B-V = 1.06

 

Frank


Edited by freestar8n, 01 April 2018 - 03:31 AM.

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#14 Aquarellia

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Posted 02 April 2018 - 12:29 AM

Tonight 2018/04/01 19:33 UTC I measured visualy this nova at +10.6.

This fluctuation looks in line with the BrooksObs explanation post here before.

Michel



#15 vakulenko_sergiy

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Posted 03 April 2018 - 06:34 PM

I have a chance to observe nova few hours ago, my estimate is СV mag = 10.3 (CCD, unfiltered with V zeropoint).



#16 Artom

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Posted 03 April 2018 - 07:41 PM

2018 Apr. 10.74 UT

m=10.6 Vis

11.4 Newtonian (77x)

Simeiz observatory, Crimea



#17 robin_astro

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Posted 04 April 2018 - 02:21 PM

Spectra by Joan Guarro Flo on the ARAS forum show increasing H alpha, H beta emission over the last few days

http://www.spectro-a...start=10#p10408

 

Robin


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#18 BrooksObs

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Posted 04 April 2018 - 02:55 PM

Spectra by Joan Guarro Flo on the ARAS forum show increasing H alpha, H beta emission over the last few days

http://www.spectro-a...start=10#p10408

 

Robin

 

The appearance and increasing intensity of the Ha emission in Nova CMa 2018's spectra marks that the nova's outburst has definitely passed through maximum. At the same time the nova's light curve further reveals it to be a definite slow nova.

 

After peaking at a magnitude of 10.0-10.2 on March 29.5 UT, the nova quickly fell by better than a full magnitude and reaching 11.5 only two days later. Immediately at this point the decline halted and the nova once more began to rise, attaining a magnitude of 10.5 by April 2.0UT, then seemed to begin another fluctuation cycle. This is the very same sort of behavior that Nova SCT 2017 exhibited last year, albeit with Nova CMa displaying it on a rather less energetic scale.

 

Experiencing a long run of cloudy weather currently, it is unlikely that I will see the nova further prior to it passing behind trees to the southwest of my observing site.

 

BrooksObs 



#19 BrooksObs

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Posted 06 April 2018 - 08:39 AM

Last evening (April 6.04 UT) I had the opportunity to give Nova CMa 2018 a look during a short interval of clear skies as twilight was ending. Somewhat surprisingly its current post-maximum brightness fluctuation has taken it to magnitude 10.1 , matching the peak of the nova's primary maximum of about a week ago. It will be interesting to see if it continues to rise any further over the weekend. Might it actually surpass the brightness of the primary maximum in luster, as nova of this type are occasionally seen to do? 

 

BrooksObs


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#20 nytecam

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Posted 07 April 2018 - 04:55 AM

There was Nova CMa 1934, well before your lifetime.

But not before mine!   Born that year ;-)

Nytecam


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#21 Artom

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Posted 07 April 2018 - 02:59 PM

2018 Apr. 07.75 UT

m=10.4 Vis

11.4 Newtonian (77x)

Simeiz observatory, Crimea



#22 freestar8n

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Posted 08 April 2018 - 06:49 AM

I started measuring this nova on the evening of March 31 in Australia and have had pretty clear skies for many days.

 

The first measurement was with a 30 second exposure in Sloan filters and was about right - but the next time I measured it was quite saturated and I needed to switch to 15 seconds.  On the third night I went down to 5 seconds.  So it was quite clear it was brightening.

 

Here is a plot with i' r' g' Sloan filters calibrated using over 100 field stars with Sloan magnitudes - corrected for second-order extinction.

 

It is cloudy now but I expect more measurements in the coming days.

 

Frank

Attached Thumbnails

  • NovaGraph1.png

Edited by freestar8n, 08 April 2018 - 07:03 AM.


#23 Artom

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Posted 08 April 2018 - 04:00 PM

N CMa 2018

2018 Apr. 08.75 UT

m=11.5 Vis

11.4 Newtonian (77x)

Simeiz observatory, Crimea

 

Star is much fainter then day ago.



#24 vakulenko_sergiy

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Posted 08 April 2018 - 08:40 PM

Yesterday I have measured CV mag 11.4 for N CMa 2018.



#25 freestar8n

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Posted 09 April 2018 - 07:04 AM

Well - quite a difference in 48 hours.  Too bad it was cloudy last night - I would have liked that data point.

 

That's a change of 1.36 mags i', 1.62 mags r', 1.87 mags g'

 

All consistent with switching from 5s exposures back to 20s

 

I also show the g'-r' color index plot - which shows it getting redder.

 

Frank

 

NovaGraph8Days.png

 

NovaColorIndex8Days.png




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