Outburst of RX J0909.8+1849: new eclipsng dwarf nova!

(Post-outburst eclipse light curve by Gordon Garradd)

Outburst detection

H. Maehara (Saitama, Japan) reports (unconfirmed) outburst of RX J0909.8+1849, a ROSAT-selected cataclysmic variable. The object is normally at V=16.4, and was recorded in outburst on the GSC plate (mag 12.53). Confirmatory and follow-up observations are strongly urged.

  YYYYMMDD(UT)   mag  observer
  19991103.130  <145  (T. Kinnunen)
  19991104.119  <150  (T. Kinnunen)
  19991105.807  <140  (T. Watanabe)
  19991130.119  <145  (T. Kinnunen)
  19991208.990  <145  (T. Kinnunen)
  19991210.751  <140  (T. Watanabe)
  19991214.960  <145  (T. Kinnunen)
  19991216.919  <145  (T. Kinnunen)
  20000103.691  <142  (T. Watanabe)
  20000104.626  <139  (T. Watanabe)
  20000122.980  <140  (T. Kinnunen)
  20000201.819  <145  (T. Kinnunen)
  20000210.692   130  (H. Maehara)

(vsnet-alert 4178)

RXJ0909.8+1849 outburst confirmed

T. Watanabe has confirmed the first-ever detection of outburst of RX J0909.8+1849 since the discovery!

Visual magnitude estimates by VSOLJ members

object         YYYYMMDD(UT)   mag  code
RXJ0909.8+1849 20000211.625   137  Wnt.VSOLJ  outburst confirmed

Observer's code:
  Wnt: T. Watanabe (Shizuoka, Japan)

(vsnet-alert 4179)

The coordinates of RX J0909.8+1849 are

   09h 09m 50.56s  (J2000.0)
   +18o 49' 47".2

Regards,
Taichi Kato

International observation campaign on VSNET finally revealed the nature!

(vsnet-alert 4180)

We started time-series photometry on RX J0909.8+1849 from 16:30 (UT) at Kyoto and also confirmed its outburst with magnitude about 14. Our run will last for 4 hours. More observations are encouraged.

Regards,
Makoto Uemura and Taichi Kato

(First-ever time-resolved photometry of an eclipse during outburst!, Kyoto team)

(vsnet-alert 4183)

RX J0909.8+1849 (UG)

RXJ0909.8+1849  20000203.443  149C  Scp
RXJ0909.8+1849  20000204.293  149C  Scp
RXJ0909.8+1849  20000207.432  129C  Scp
RXJ0909.8+1849  20000210.303  148C  Scp
RXJ0909.8+1849  20000211.316  135C  Scp
Sequence:   USNO-A2.0 (red magnitudes)
Instrument: IRO (0.5-m RCT + AP-8)

This outburst looks pretty strange. Either on Feb. 7 the object underwent a precursor outburst to the current (super?)outburst, or an eclipse was observed on Feb. 10.303 UT. I have already brought this interesting fact to Tonny Vanmunster's, Taichi Kato's and Makoto Uemura's attention in time for their observing runs tonight. Hopefully they will be able to clarify the situation. Anyway, superhumps and/or eclipses are very probably awaiting their detection, and time-resolved photometry throughout the outburst are very strongly recommended.

USNO-A2.0 data for RX J0909.8+1849: 090950.571 +184948.15 (2000.0) 15.2 15.8

(vsnet-alert 4184)

Hi colleagues,

I started observing RX J0909.8+1849 at CBA Belgium Observatory, using = the 0.35-m f/6.3 telescope with unfiltered ST-7 CCD, at about 20h08m UT. = I turned on my "real-time" light curve facility, allowing me to follow = the evolution of the light curve of this object as closely as possible. = My first excitement came when I noticed the development of hump-like = features (with a small amplitude). I'm not sure yet if these are real = superhumps.

This however was just the beginning of the "show". A little later, the = variable started a fast fading - entering a deep eclipse - to recover = about 28 minutes afterwards. You could call it a UG+E detection in = "real-time".

Here are some first details :

Eclipse depth : 2.5 magnitudes
Eclipse duration (estimate looking at light curve) : 28 minutes
Mid-eclipse (estimate looking at light curve) : 2000 Feb 11.8845 UT

I'll continue monitoring this object for the rest of the night = (evidently).

What an exciting hobby !

Best regards,
Tonny

(vsnet-alert 4189)

Dear colleagues,

I have been able to observe a second (consecutive) eclipse of RX = J0909.8+1849, during tonight's run at CBA Belgium Observatory. This has = enabled me to determine the orbital period of the system, which is = 0.1751d or 4h12m.

This value very well explains the Feb 10.303 UT observation Patrick = Schmeer refers to in his vsnet-alert message 4183. He has indeed made an = image at the moment of an eclipse.

Clouds have now entered the Belgian skies. I hope someone else will be = able to take over on this interesting object ...

Best regards,
Tonny Vanmunster
CBA Belgium Observatory

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