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Alert Notice 313: 2005+39 N Cygni 2005 AND 1258-49 SN 2005af in NGC 4945 (Centaurus) AND Reminder to monitor 0749+22 U Geminorum

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February 11, 2005

SUBJECTS:

1. 2005+39 N CYGNI 2005
2. 1258-49 SN 2005af in NGC 4945 (CENTAURUS)
3. REMINDER TO MONITOR 0749+22 U GEMINORUM

1. 2005+39 N CYGNI 2005

Event: Possible nova

Discovered By: Hideo Nishimura, Kakegawa, Shizuoka-ken, Japan (reported by S. Nakano, Sumoto, Japan, IAU Circular 8483)

Discovery Magnitude: magnitude 9.7 on two T-MAX 400 films taken using a Pentax 6x7 camera (+ 200-mm f/4.0 lens, limiting magnitude 11) (IAU Curcular 8483)

Discovery Date: Feb. 10.85 UT (IAU Curcular 8483)

Position: from S. Wakuda, Yuto, Shizuoka-ken, Japan, average of eight measurements from a CCD image taken on Feb. 11.841 UT (IAU Curcular 8483) R.A. = 20h 09m 19.05s (equinox 2000.0) Decl. = +39o 48' 52.9" (equinox 2000.0)

AAVSO Chart(s): N Cyg 05 Charts [obsolete link; create charts using VSP at http://www.aavso.org/vsp and use name Nova Cyg 2005]

Report Object to the AAVSO as: 2005+39 N CYG 05

Observations Reported to the AAVSO: Feb. 11.761, 8.9 CCD, K. Kadota, Ageo, Saitama-ken, Japan (via IAUC 8483); Feb. 11.841, 9.3 CCD, S. Wakuda, Yuto, Shizuoka-ken, Japan (via IAUC 8483).

Notes (from IAU Circular 8483):

a. Nishimura reported nothing was visible at this position on his patrol films back to 2001 Oct. 21 (including one taken on 2005 Feb. 6 with limiting mag 11).

b. Nishimura reported a semi-accurate position of R.A. = 20h 09m 19s, Decl. = +39o 48' 49" (equinox 2000.0).

c. K. Kadota, Ageo, Saitama-ken, Japan, provided position end figures 19s.09, 52.2" from a CCD image taken with a 0.25-m f/5.0 reflector on Feb. 11.761 UT.

d. The nearest object in the USNO-A2.0 catalogue lies 14" to the southeast (red mag 16.4).

Congratulations to Hideo Nishimura on his discovery!

2. 1258-49 SN 2005 in NGC 4945 (CENTAURUS)

Event: Possible supernova

Discovered By: C. Jacques and E. Pimentel Belo Horizonte, Brazil (IAU Circular 8482)

Discovery Magnitude: CCD magnitude 12.8, images taken using a 0.30-m Schmidt-Cassegrain reflector during CEAMIG/REA supernovae search (IAU Circular 8482)

Discovery Date: Feb. 8.22 and 10.23 UT (IAU Curcular 8482)

Position: 407" west and 351" south of nucleus of NGC 4945 (IAU Circular 8482)
R.A. = 13h 04m 44.06s (equinox 2000.0)
Decl. = -49o 33' 59.8" (equinox 2000.0)

AAVSO Chart(s): An AAVSO chart is being prepared and will be posted on the AAVSO website http://www.aavso.org.

Report Object to the AAVSO as: 1258-49 SN NGC4945 (if the object is confirmed as a supernova, the name will be updated with the standard-format name, which will be announced on the AAVSO website and in other locations)

Notes (from IAU Circular 8482):

a. Nothing was visible at this position on a CCD image by Jacques on 2004 June 20.93 UT (limiting magnitude 18.5) or on a 1976 red Digitized Sky Survey plate.

b. The possible supernova lies in a quite rich area of foreground Milky Way stars in Centaurus.

Congratulations to C. Jacques and E. Pimentel on their discovery!

3. REMINDER TO MONITOR 0749+22 U GEMINORUM

As mentioned in AAVSO Alert Notice 312, our colleague Dr. John Cannizzo, NASA Goddard Space Flight Center, plans to observe the next outburst of the cataclysmic variable U Gem with RXTE, on a Target Of Opportunity (TOO) observing campaign. Prompt notification of when U Gem has started its rise to outburst will be crucial for Dr. Cannizzo to start his TOO observations. U Gem was last in outburst in mid-September, when it brightened to magnitude 9.2 and was brighter than 11.0 for 14 days.

Your excellent coverage of this star to date is much appreciated - thank you!

Please continue to monitor U Gem's activity very closely, and notify Headquarters immediately if the star brightens to magnitude 13.5 or brighter. Both visual and CCD observations are encouraged.

** NEW CHARTS FOR U GEM WERE ISSUED IN FEBRUARY 2004 ** and are available on the AAVSO website. Please make sure you are using these latest charts. If you do not have access to the website, please contact Headquarters and ask for the new charts to be sent to you.

SUBMIT OBSERVATIONS TO THE AAVSO

We encourage observers to submit observations via our web site (online data submission tool WebObs), or by email in AAVSO format to observations@aavso.org [obsolete address]. If you do not have AAVSO Observer Initials, please contact Headquarters so we may assign them to you. The answering machine at AAVSO Headquarters is on nights and weekends; use our charge-free number (888-802-STAR = 888-802-7827) to report your observations, or report them via fax (617-354-0665).

Many thanks for your valuable astronomical contributions and your efforts.

Good observing,

Elizabeth Waagen
Interim Director

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