Daisaku Nogami
Dear Colleagues,
John Day (Leicester, UK) reports an outburst of V725 Aql. Confirmation has come from G. Poyner (Birmingham, UK). Details...
Aug 11.9889 <14.2 Poyner 40cm
12.8902 13.5 Day 40cm
12.9027 13.5 Poyner
12.9097 13.5 Poyner
This star is monitored as part of the TA/BAA Recurrent Objects Programme.
Further observations are encouraged.
Regards,
Gary Poyner
Dear Colleagus,
During the course of our systematic survey of dwarf novae at Ouda Station, Kyoto University, we discovered a "new" bright (V~13.6) object in the vicinity of the cataloged position of V725 Aql. At the corresponding position of the CV chart by Downes & Shara, there seems to be only a very faint star (V~19?), and is clearly different from V725 Aql identified in this chart. We only know old UBV photometry of V725 Aql, which is claimed to lack ultraviolet excess. It is likely we have rediscovered "true" V725 Aql in outburst (if so, the large outburst amplitude suggests a low outburst frequency -- intensive observations during the current outburst would be therefore highly recommended). However, the cataloged range of variability of V725 Aql (13.7-16.2p) is against this interpretation. Does anyone have more information on this star? Other interpretations are also possible: a nova? a new large-amplitude variable star? (an LPV interpretaion is less likely because red-to-infrared sensitive CCD images during "quiescence" could not show a bright star at this position). No numbered minor planet was at this position. Furthermore, three sequential CCD exposures could not show any motion. Spectroscopic and/or multi-color photometry are most helpful in this stage.
We here attaches a vsnet-format V-band CCD chart for convenience of observers. We would like to hear any positive/negative observations.
Best regards,
Daisaku Nogami
Astrometry of the object in question in the field of V725 Aql
Concerning the preceding mail relaying the astrometry of the object in question, M. Iida (VSOLJ) communicates there was an error in the reduction process. Sorry for taking your time. He provides the following correct position of rediscovered V725 Aql or the "new" object in the field of V725 Aql.
19h 56m 45s.03 +10o 49' 32".7 (J2000.0) (+/-0.5 arcsec)
Reference stars: 7 GSC stars.
We hope this will help identifying the object.
Regards,
Taichi Kato and Ouda team
Dear vsnet-alert members,
After our initial alert on unidentified outbursting stellar image in the field of this variable star, we have been informed by Dr. D. Welsh (Canada, welch@physics.mcmaster.ca) of a bibliographic list of V725 Aql compiled from the "Bibliographic Catalogue of Variable Stars" and its supplements. I have been surveying the litertures listed, and found some additional information on this star.
* Bruch 1983 (IBVS 2287): UBV photometry during quiescence.
V = 15.79 +/- 0.11, B-V = 1.52 +/- 0.14, U-B = 0.60 +/- 0.47
Bruch notes that the colors resembles those of the recurrent nova
T CrB. However, one should be careful in interpreting these data
because photometry was apparently done for the object identified by
Vogt and Beteson 1982 (AsAp Sup. 48, 383) = Downes and Shara 1993
(PASP 105, 127).
* Echevarria 1984 (Mexico Rev. Astr. Astrof.): a compliation of UBV
photometry of CVs which includes the photometric data by Bruch.
* Fuhrmeister 1991 (MVS 12, 94): a survey of 250 Sonneberg plates.
Following outbursts are listed; the first three (*) are identical
with those reported in Rohlfs 1949 (Veroff. Sternwarte Sonneberg
1, Nr. 3 = discovery paper).
JD
------------------
2428040 - 8048 (*)
9429 (*)
2430704 (*)
2441921 (two plates)
2447039
These data seem to suggest a low outburst frequency of this object.
No information of identification was given.
Our library lacks two most important discovery papers for identifying what star is true V725 Aql:
Rohlfs, E. 1949, Veroff. Sternwarte Sonneberg 1, Nr. 3 Hoffmeister 1957, MVS 1, 245.Can anyone check them?
Some additional information seem to have appeared in various litertures, which we can't access.
* Petit 1960, JO 43, 17 * Schneller 1960, GUL 2.5.1 * S.V.S.O. 1987, S.V.S.O. Rep. 1986: 2.A.1 * S.V.S.O. 1987, S.V.S.O. Rep. 1986: 2.A.2 * Khruzina, Shugarov 1991: Atlas of Cataclysmic Variables (Moscow)We would like to hear any further information and observation.
Regards,
Taichi Kato and Ouda team
In reference to Kato-san's request for a check on the discovery citations for V725 Aql, I have looked at both the Rohlfs list and the Sonneberg MVS chart series.
Rohlfs' position (Ver\"off. Sternwarte Sonneberg 1, 168) is given to only 1s/0'.1 precision, and so may not be definitive:
19 49 50 +10 26.4 (1855) 19 56 44 +10 49.4 (2000)
This publication is also the source of the photo-blue magnitude range of 13.7-16.2.
The Sonneberg chart (on MVS 326 --- MVS 245, cited by Kato-san is for the introductory remarks to the series of loose-leaf charts) has rather small scale, but indicates a position somewhat south of the Vogt & Bateson or Downes & Shara charts. A possible very faint candidate lies 2.5mm = 14" south of the object marked on the Downes & Shara chart. This star, however, is much fainter than the mag. 16 quiescent brightness noted by Rohlfs. Also, the chart is small enough that a trivial error in plotting could place the variable at the position marked by V&B and D&S.
Sorry this wasn't definitive!
\Brian
Dear colleagues,
The variable star (genuine V725 Aql?) we discovered near V725 Aql on Mar. 8 was observed on the same position also on Mar. 11 at the Ouda Station. The following table shows relative V mag. of it.
mid-UT SN-comp(*1) S.D.(*2) N(*3)
----------------------------------------
950308.829 0.524 0.029 3
950311.854 0.604 0.048 5
(*1) comparison: 19h 56' 46".80 +10o 47' 02".4 (2000.0).
V=13.0 (GSC)
(*2) Standard deviation
(*3) Number of frames
The very small decline rate (~0.03 mag/day) suggests that the current outburst of this variable is long one in "SS Cyg-type" DNe, but the outburst amplitude about 6 mag. is too large for SS Cyg-type DNe.
More observaitons are highly encouraged!
Regards,
Daisaku Nogami
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