PNV J13532700-6725110: possible nova (9.1 mag) in Circinus (near the border with Musca)

Hi All

Just I was inputting my nightly observations just at morning twilight, I saw Patrick's note and hastily printed out a chart and heading back outside.  The nova suspect was easily visible (mag 8.2 at Feb 18.868UT) in a bright sky at the discovery location specified.

Regards

Andrew

There is a new sequence available for PNV J13532700-6725110.

Jim Jones

Andres Chapman (Argentina) reports V= 9.12 mag on 2018 Jan. 20.15848 UT (40-sec exposure) and co-ordinates RA 13h53m27.60s, DEC -67°25'00.7" (J2000.0; accuracy about 0.3").
A Gaia DR1 source (position end figures 27.59s, 00.9"; G= 17.28 mag) is located only 0.3" from this position, and the UV source GALEX J135327.5-672500 (position end figures 27.57s, 00.7"; NUV= 18.9 mag) is only 0.2" away.
ASAS-SN Sky Patrol observations using the co-ordinates provided by Chapman: 2018 Jan. 18.341 UT, V= 15.7 mag (probably contaminated by nearby stars); 19.340 UT, V= 8.7 mag: https://asas-sn.osu.edu/light_curves/ba602dc4-de20-40d7-9995-b6d047036d…

The AAVSO database contains already three visual observations: https://www.aavso.org/apps/webobs/results/?star=PNV+J13532700-6725110

I will start observations from ROAD Chile the next night, weather permitting in BVI filters.

Josch

2018 01 20.5916 UT
Strong hydrogen emission line was detected in my low-resolution spectroscopic image taken with T17 0.43-m f/6.8 CDK astrograph + FLI PL4710 CCD at SSO, NSW, Australia.
http://meineko.sakura.ne.jp/ccd/PNV_J13532700-6725110-spe.jpg

2018 01 20.5868 UT
Photometry results were B=8.62, V=8.48, Rc=8.37 and Ic=8.22 with T17 0.43-m f/6.8 CDK astrograph + FLI PL4710 CCD at SSO, NSW, Australia.

Seiichiro Kiyota (Kamagaya, Japan)

I observed the nova and brightnesses are:

V = 8.45 +/- 0,02

B = 8,83 +/- 0,03

I = 7,88 +/- 0,03

using AAVSO comp stars BMN 677 and 679.

Josch

Hi all

This object appears to be gradually brightening. I've been making DSLR obs.

Was there an alert notice? Perhaps I missed it.

David

I agree David, it seems to have risen noticeably since discovery.  I took a low-res optical spectrum tonight and it seems virtually featureless.

Cheers -

Rob  KBJ

Hi David -

Yes, I took another low-res optical spectrum on 27.56 Jan UT and it was still showing no emissions.  A high-res spectrum may show more.  Incidentally, I used 30-sec exposures and they gave me a much stronger spectrum than the 150-sec exposures I used a week ago!  It has brightened a lot.

Visually I made it out at 6.6 on 27.46 Jan UT but tonight (28 Jan) I had clouds.  But I did see it for a few seconds in a brief gap - not long enough to do an obs against the AAVSO comp stars but it seemed brighter against the adjacent star TYC 9243 2305 (V 5.7) than it did last night and it wouldn't surprise me if it was brighter than 6.4.  Time will tell, looking forward to seeing what comes into the database.

Cheers -

Rob Kaufman  KBJ

Went outside just after I posted the last message and there was a small break in the clouds.  I made the nova out at 6.4 visually through 10x50 binoculars (28.63 Jan 2018 UT).  Could not see N Mus 2018 because of cloud.

Cheers -

Rob Kaufman  KBJ

AAVSO Alert Notice 613 announces and reports on Nova Cir 2018 = PNV J13532700-6725110. Please see the notice for details and observing instructions. ToO observations with the Fermi Gamma-Ray Telescope are underway and special optical coverage is needed in support.

Many thanks and Good observing!

Elizabeth Waagen, AAVSO HQ

This nova dropped almost a magnitude on 28/29 Jan, in 24 hours by visual observations in the database.  It went from a level 6.4 to a level 7.3-7.4.  However I observed, imaged and took a rough spectrum of it through variable cloud about 7 hrs before the reported drop to 7.3 (insufficient to do a proper obs) and it was still bright, similar to what it had been the night before.  So the drop may have occurred in a period of just 7 hours.

Last night (31 Jan 2018), during the total lunar eclipse, I took a low-res optical spectrum and saw emission lines (H-alpha, H-beta & FeII) for the first time since 20 Jan.  The lines were clear but reasonably weak. Spectra I'd taken on 25, 27 & 29 Jan all showed no emissions and a fairly featureless continuum.

This nova is worth watching closely if you're far enough south.

Cheers -

Rob Kaufman  KBJ

Cool. I pointed to your spectrum in this post Rob:

  https://dbenn.wordpress.com/2018/02/03/nova-cir-2018-gamma-ray-space-telescope-observations/

I've been taking as many TB,G,R DSLR obs as possible. Not sure whether it will be clear tonight.

I have a question about novae and the Fermi Gamma-ray Space Telescope: how often is Fermi pointed at novae and has this been happening for long? I see that N Mus 2018 has also been a recent target. More generally, I'm just curious to know more about the criteria applied to decide when Fermi or some other instrument is pointed at novae.

David

Hi David,

The most important thing to note is that Fermi LAT (Large Area Telescope) is not a narrow field-of-view telescope - it's a wide field-of-view, all-sky survey mission. "With its very large field of view, the LAT sees about 20% of the sky at any given moment. In sky-survey mode, which is the primary observing mode, the LAT will cover the entire sky every three hours." (https://www.nasa.gov/content/goddard/fermi-spacecraft-and-instruments) In the sky-survey mode, the LAT will have more-or-less equal sensitivity to every part of the sky. When we "point" LAT at a nova, actually it still carries out an all-sky survey - just with an enhanced exposure time for the sky around the target, improving the sensitivity by about a factor of 2 (and hence sacrificing the sensitivity for objects in other parts of the sky). Since novae are transient gamma-ray sources, and even the bright ones are not that much above the daily or weekly detection limit of Fermi LAT, this factor of ~2 improvement in sensitivity really helps. Sometimes, a pointed observation of one nova also helps with the sensitivity for another nearby nova, like V5855 Sgr and V5856 Sgr in 2016 ("nearby" compared to the size of the LAT field-of-view).

During the first 5 years of the Fermi mission, three novae (V407 Cyg, V1324 Sco, and V959 Mon) were detected in sky-survey mode. Pointed Fermi observations of novae started in 2013 with V339 Del. The early ones were requested by Dr. Teddy Cheung of Naval Research Laboratory, who is a member of the Fermi team. More recently, my colleague Prof Laura Chomiuk of Michigan State University and I have been the ones to make the request - and the Fermi mission team has been very accomodating (although I was turned down a couple of times last year due to other constraints). We tend to pick the optically bright, hopefully nearby novae for which we have the best chance of detection. Currently, we request pointed observations of any confirmed novae whose peak magnitude is brighter than about 10th.

Hope this note was useful.

Koji

I took spectra of both Nova Cir 2018 and Nova Mus 2018 last night in the Ha region. They both have quite broad Ha emission but the expansion velocity of Nova Mus is much higher. Ity is interesting to compare them.

Terry

Last night (17 Feb) I did a binocular visual obs of this nova which appears to be fading and my measure was way out of kilter with other obs received.  I've checked the comp stars and found what partly but not fully explains the discrepancy - the 78 comp star has a very close companion only about a magnitude dimmer.  Might be OK for narrow-field CCD photometry but they appear as one through binoculars so not suitable for use for that purpose.  I'm happy to cop the remainder of the discrepancy but I'll remove the obs from the database in any case as it is obviously flawed.  Promise to do better tonight if the clouds allow!!

Cheers -

Rob Kaufman KBJ

Hi All

This nova continues to surprise. Currently it’s brighter than 6th magnitude and has risen steeply over the last few days.

Regards

Andrew

After peaking around V= 5.8, the star dropped two magnitudes in three days.

Around 8th magnitude there were problems with the sequence: the 78 comp star was actually a 24" double with a 9th mag. companion and a combined brightness of 7.5 so it was dropped from the sequence.
74 and 79 comp stars were added so please update your charts.

Cheers,
Sebastian
 

Sorry, Padilla.
Have you got anything written in the space "Chart ID"? That may be the problem. Or have you got anything written alongside "What will be the title for this chart?"

Best wishes in resolving your problem.

Stephen