V2573 Oph = Nova Oph 2003

(Takao's discovery image on July 16.514 UT)

(CCD image by Berto Monard)

(CCD image by Greg Bolt)

(Image by Paulo Cacella and the DSS image)

(vsnet-discovery-nova 216)

Possible Nova in Ophiuchus

Dear Colleagues,

Akira Takao (Kitakyushu, Japan) reports the detection of a likely new object on his two unfiltered CCD images taken on July 10 and 16. The reality of the object was confirmed on multiple CCD images taken with different image centers. Takao's observations are summarized as below (the object's name is tentatively assigned here):

object         YYYYMMDD(UT)   mag  code
OPHnova2003?   20010418.806  <126C  Toa.VSOLJ
OPHnova2003?   20020318.808  <116C  Toa.VSOLJ
OPHnova2003?   20020512.647  <116C  Toa.VSOLJ
OPHnova2003?   20030418.812  <116C  Toa.VSOLJ
OPHnova2003?   20030710.598  114C  Toa.VSOLJ
OPHnova2003?   20030716.523  112C  Toa.VSOLJ

The magnitude were derived from GSC 6833.117, GSC 6833.89, GSC 6833.101. The instruments were f120mm F4 Telephotolens, ST-8, unfiltered.

Takao reports the approximate position of the object (maximum 20 arcsec uncertainty) as follows:

    17h 19m 14s.4 (J2000.0)
      -27o 22' 37"

There is no bright 2MASS star nor an IRAS source.

According to ASAS-3 public data, this object was recorded to brighten on June 15. After maintaining magnitudes of V=11.0-11.5, the object apparently reached a maximum of V=10.6 on June 26. The corresponding part is shown below. [The dates have been corrected from the original posting].

HJD-2450000   V   error
========================
2805.68946 11.212 0.061  ASAS-3 outburst detection
2809.71132 10.813 0.048
2809.82674 11.340 0.024
2810.63091 11.426 0.088
2810.83013 11.551 0.047
2811.69979 11.452 0.023
2812.63353 11.077 0.047
2812.84579 11.077 0.023
2813.80357 10.902 0.048
2816.83935 10.591 0.022  maximum?
2819.68174 10.799 0.077
2821.58933 10.880 0.039
2833.60945 11.704 0.054
2833.63153 11.647 0.077
2834.72946 11.550 0.042
2836.58633 11.306 0.066

The last ASAS-3 negative detection was about 11 days before this initial detection, but this negative detection should be treated with caution because ASAS-3 may have simply failed to pick up the object. Prior to the present outburst, there was no indication of meaningful detection by ASAS-3 in the past.

The similarity of the V-band and unfiltered CCD magnitudes indicate that the object is not a red variable. The light behavior suggests some sort of an eruptive object such as a nova.

Spectroscopic confirmation as well as precise astrometry is very urgently requested to reveal the nature of the object.

Regards,
Taichi Kato

(vsnet-discovery-nova 217)

Date: Thu, 17 Jul 2003 17:26:28 +1000
From: Vello Tabur 
Subject: Re: [vsnet-newvar 2054] Possible Nova in Ophiuchus

Oops! I first detected this object in the course of my own survey on June 16 but mistook it for a variable. I even assigned a number for it in my own catalog of variables that I can detect with my equipment! I took numerous images when I first noticed it (waiting for it to move; hoping for a comet) but when it didn't, I catalogued it and moved on especially since it was visible (but much fainter) on previous images. Here is a list of prediscovery observations using an unfiltered 140mm f/2.8 telephoto lens + ST8.

YYYYMMDD    JD               CCD-R
20030321    2452720.10023    12.9
20030405    2452735.15183    13.1
20030429    2452759.07862    13.2
20030504    2452764.06586    13.1
20030510    2452770.03739    13.1
20030522    2452782.16690    13.0
20030529    2452789.09510    12.6
20030616    2452807.03354    10.1
20030616    2452807.04613    10.2
20030616    2452807.06032    10.3
20030616    2452807.08168    10.3
20030616    2452807.10305    10.1
20030705    2452826.07376     9.8

An updated position based on my images is 17h 19m 14s.2 -27d 22' 34" (+/- 5") J2000

-- 
Vello Tabur
Comet Hunting Techniques    http://www.tip.net.au/~vello
R&D, SearchSoftwareAmerica  http://www.searchsoftware.com

Further explanation by Tabur

(vsnet-discovery-nova 218) Vello Tabur's updated position more critically confirms the absence of a bright 2MASS star. The object is certainly not a red variable. Possibly a slow nova, which underwent a major brightening in June? (Other possibilities naturally remain).

Regards,
Taichi Kato

(vsnet-discovery-nova 220)

I just visually confirmed this new object. Comp stars were TYC6833-0286-1 (V=10.65) and TYC6833-0078-1 (V=11.22) magnitudes from Tycho2+Bessell corrections.

N?OPH 20030717.4430 10.8 LMK

Mike Linnolt
Honolulu, HI

(vsnet-discovery-nova 221)

Date: Thu, 17 Jul 2003 20:33:48 -0400
From: "W.Liller" 
Subject: Possible nova in Oph
Hola Taichi -

Here is what I can tell you about the possibile nova in Oph:

     object         YYYYMMDD(UT)   mag  code   

OPHnova2003?   20030607.117   <11.1R LIL
OPHnova2003?   20030623.132    10.4R LIL
OPHnova2003?   20030714.985    11.1R LIL

All observations were with Kodak TP film, an orange filter, and an 85mm f/1.5 Nikon lens. Uncertainties +/- 0.2 mags.

All the best, Bill Liller

(vsnet-discovery-nova 222)

The probable Nova was imaged at the Bronberg Observatory with the unfiltered CCD camera.

In comparison to the image from the DSS-2/red, a new and bright object showed on the image. Astrometry traceable to the UCAC1 frame gives (2000) coordinates:

17 19 14.10 -27 22 35.4 (+/- 0.2" estimated)

The unfitered CCD observation (UT) :

Nova Oph03 20030717.821 10.4CR (UCAC1 reference)

Note: compared to the recent estimate by M Linnolt, this CR magnitude confirms the new star as non-red.

Regards,

Berto Monard
Bronberg Observatory / CBA Pretoria

Spectroscopy

Hola everyone -

Last night, July 18.15 UT, through thin clouds, I was able to get a CCD objective grating spectrogram of the possible nova in Ophiuchus. H-alpha is present and strong in emission, some 12 times the intensity of the surrounding continuum. Its FWHM = 1450 km/sec.

Here is what I have for the magnitudes:

object YYYYMMDD(UT) mag code comments

OPHnova2003   20030607.117  <11.1R    LIL   Red photographic*
OPHnova2003   20030623.132    10.4R    LIL   Red photographic*
OPHnova2003   20030714.985    11.1R    LIL   Red photographic*
OPHnova2003   20030718.114    11.29V  LIL   CCD through clouds, +/- 0.07 mag 
OPHnova2003   20030718.116    12.13B  LIL   CCD through clouds, +/- 0.07 mag

Thus, the nova has a B-V of approximately +0.8.

All the best to all, Bill Liller

* Made with Kodak TP film, an orange filter, and an 85mm f/1.5 Nikon lens.

Uncertainties +/- 0.2 mags.