V4745 Sgr = Nova Sgr 2003

(CCD image by Ken-ichi Kadota)

Nova Sgr 2003

According to IAUC No. 8123, Nicolas J. Brown (Australia) and Minoru Yamamoto (Okazaki, Japan) independently discovered a candidate nova in Sgr. The accurate coordinates of the object are:

    18h 40m 02s.54                   02s.57
    -33o 26' 55"1                     55".5
    (J2000.0, measured by Kushida)  (end figures by K. Kadota)

The object is reported to be different from a nearby variable star V2377 Sgr. The nova was not detected on Apr. 5 film by Yamamoto.

A spectrum taken by Skuljan showed numerous broad and bright emission lines on a generally weak continuum. From this description, the object is confirmed to be a nova.

Kilmartin reported a possible precursor (blended) with R = 17.9 +/- 0.4, although Kushida reported that nothing was present on DSS red and blue images. Accurate identification of the quiescent counterpart is still needed.

   Reported magnitude using the VSNET format:
   (please use SGRnova2003 until the permanent GCVS name is issued).

SGRnova2003 20030425.73 89p NBr
SGRnova2003 20030426.735 96p Ymo
SGRnova2003 20030427.677 93C KuR
SGRnova2003 20030427.667 9.36V AGi
SGRnova2003 20030427.667 9.22B AGi
SGRnova2003 20030427.667 8.38U AGi
SGRnova2003 20030427.667 8.82Rc AGi
SGRnova2003 20030427.667 8.99Ic AGi
SGRnova2003 20030426.67 85 NBr
SGRnova2003 20030427.531 90 Stu
SGRnova2003 20030427.543 93 AGi
SGRnova2003 20030427.738 91 Jon

The description of the spectrum suggests that the nova has already significantly faded from the maximum. If the proposed quiescent counterpart is correct, the observed amplitude also suggests that the true maximum may have been missed betwwen April 5 and 25, or the object may be related to a small-amplitude recurrent nova.

Further search for photograhs, CCD images and other available material around the gap of observation and past materials is encouraged.

Regards,
Taichi Kato

(vsnet-discovery-nova 194)

Nova Sgr 2003: observation details by Yamamoto

We have received the following observation details from Minoru Yamamoto. The negative observations may not necessarily be limiting magnitudes, but sometimes more represent safe upper limits to confirm the absence of a brightening.

object         YYYYMMDD(UT)   mag  code
SGRnova2003    20000428.701  <105p  Ymo.VSOLJ
SGRnova2003    20000607.622  <105p  Ymo.VSOLJ
SGRnova2003    20000708.610  <105p  Ymo.VSOLJ
SGRnova2003    20000802.531  <110p  Ymo.VSOLJ
SGRnova2003    20000829.526  <105p  Ymo.VSOLJ
SGRnova2003    20010329.789  <105p  Ymo.VSOLJ
SGRnova2003    20010404.798  <105p  Ymo.VSOLJ
SGRnova2003    20010626.610  <105p  Ymo.VSOLJ
SGRnova2003    20010720.581  <105p  Ymo.VSOLJ
SGRnova2003    20010822.556  <105p  Ymo.VSOLJ
SGRnova2003    20010912.460  <105p  Ymo.VSOLJ
SGRnova2003    20020311.827  <105p  Ymo.VSOLJ
SGRnova2003    20020421.762  <105p  Ymo.VSOLJ
SGRnova2003    20020518.735  <109p  Ymo.VSOLJ
SGRnova2003    20020618.698  <105p  Ymo.VSOLJ
SGRnova2003    20020711.548  <105p  Ymo.VSOLJ
SGRnova2003    20020829.442  <105p  Ymo.VSOLJ
SGRnova2003    20020923.406  <105p  Ymo.VSOLJ
SGRnova2003    20021010.398  <105p  Ymo.VSOLJ
SGRnova2003    20030307.825  <105p  Ymo.VSOLJ
SGRnova2003    20030308.778  <105p  Ymo.VSOLJ
SGRnova2003    20030311.826  <95p  Ymo.VSOLJ
SGRnova2003    20030329.801  <95p  Ymo.VSOLJ
SGRnova2003    20030405.774  <105p  Ymo.VSOLJ
SGRnova2003    20030426.735   90C  Ymo.VSOLJ *
SGRnova2003    20030426.735   96p  Ymo.VSOLJ
SGRnova2003    20030426.736   96p  Ymo.VSOLJ
SGRnova2003    20030426.778   89C  Ymo.VSOLJ *
SGRnova2003    20030427.784   91C  Ymo.VSOLJ *
SGRnova2003    20030427.785   85C  Ymo.VSOLJ *

Observer's code
  Ymo: M. Yamamoto (Aichi, Japan)
  Instruments: f200mm F4 with PO0 + Tmax400(120)
               *85mm F2.8(F1.8) + Finepix S2Pro(CCD)
Seq:H/T

Prediscovery Detection by Nishimura

(vsnet-discovery-nova 198)

V4745 Sgr: prediscovery detection by Nishimura

We have received the following observations from Hideo Nishimura, who positively detected V4745 Sgr on Apr. 12 (UT). Unfortunately, Nishimura did not pursue the object because of the presence of a nearby Mira-star V2377 Sgr, although he had recognized the object. He also presents the upper limit observations on Apr. 9 (UT), which can severely constrain the time of the major rise.

Photographic magnitude estimates by VSOLJ members

object         YYYYMMDD(UT)   mag  code
SGRV4745       20030408.78985 <120p  Nmh.VSOLJ
SGRV4745       20030409.75887 <110p  Nmh.VSOLJ
SGRV4745       20030412.76549  85p  Nmh.VSOLJ
SGRV4745       20030421.73014  85p  Nmh.VSOLJ
SGRV4745       20030426.73412  92p  Nmh.VSOLJ

Observer's code:
  Nmh: Hideo Nishimura (Kakegawa, Shizuoka, Japan)
       Instruments: 200mm F/4 lens + T-Max 400 unfiltered

Prediscovery Detection by the ASAS Survey

(vsnet-discovery-nova 199)

V4745 Sgr: prediscovery detection by ASAS survey

We have received the following report. The observation on Apr. 10 must have caught the object on the rise. There seems to have been a short premaxium halt, and a rise to (at least) V=7.4!

From: Grzegorz Pojmanski 
Date: Wed, 30 Apr 2003 12:52:28 +0200 (CEST)

Dear Taichi Kato,

ASAS has measured the following light curve of V4745 Sgr:

object           HJD      YYYYMMDD(UT)     mag   inst

SGRV4745     2737.85456   20030408.35456 <14.0V ASAS3V
SGRV4745     2739.86553   20030410.36553 10.63V ASAS3V
SGRV4745     2741.83844   20030412.33844  8.37V ASAS3V
SGRV4745     2743.83514   20030414.33514  8.02V ASAS3V
SGRV4745     2744.85345   20030415.35345  7.80V ASAS3V
SGRV4745     2747.86327   20030418.36327  7.41V ASAS3V
SGRV4745     2755.78626   20030426.28626  9.26V ASAS3V
SGRV4745     2757.79449   20030428.29449  9.32V ASAS3V
SGRV4745     2759.85935   20030430.35935  9.44V ASAS3V

Please note, that any photometric measurement of the ASAS3V system is available over the internet within 5 minutes after observation. It takes about 1.5-2 nights to cover the whole sky, so most of the recent measurements of any object are only 0-2 days old.

One can access current (and archive) photometry of any object directly from http://www.astrouw.edu.pl/cgi-asas/asas_lc/

where ID has format HHMMSS-DDNN.N 
        HHMMSS - right ascension, 
        [+or-]DDNN.N - declination (DD -degrees, NN.N - minutes)
e.g.

SGRV4745 http://www.astrouw.edu.pl/cgi-asas/asas_lc/184002-3326.9

CCD photometry and Chart by Doug West

(vsnet-campaign-nova 1214)

I placed a finder chart for the new nova in Sgr that was just announced in IAUC 8123 at http://members.aol.com/dwest61506/page70.html. My initial observations are:

nova sgr 2003-01  20030427.45  9.65V  WJD  Based on Tycho 2 mags
nova sgr 2003-01  20030427.46  8.90Rc  WJD  Based on Tycho 2 mags

Doug West
http://hometown.aol.com/dwest61506/index.html

Chart by Sebastian Otero

(vsnet-chart 441)

A preliminary chart for Nova Sgr 2003 is available at: http://ar.geocities.com/varsao/Carta_V4745_Sgr.htm

Regards,
Sebastian.

Chart by Japan Variable Stars Study Association

Chart

2MASS information

(vsnet-discovery-nova 190)

I have just checked the 2MASS public images of this field. The location of the nova is almost blank. This non-detection in the 2MASS survey images indicate that the possibility of a giant secondary (as in a symbiotic nova or symbiotic recurrent nova) is less likely among possibilities. This may also suggest that the true quiescent counterpart may be fainter than the quoted value by Kilmartin.

V2377 Sgr is clearly recognized as a bright star on 2MASS images, supporting its published identification.