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DE CNC

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pukemaru
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This star is classified as a UG with a range of 14.6-18.0p.

Since, 1 January 1993, there have been 2010 visual observations, BUT only 6 positive sightings.
4 have been around 18.0 which is minimum.
1 has been at 15.7, and was made by an expereinced observer. I note that on the night before and the night after, the variable was recorded at <15.7, and I suspect it should have been recorded at <15.7 as well.
1 has been at 13.0, again by an expereinced observer BUT no chart nor comparion stars are given and it was the only observation of this star by this observer.There is a 13.0 in the field and I wonder if this was mistaken for the variable.

I note that there have been 853 CCD observations, many of them positive at around 17.0-19.0 with some as bright as 16.3.

So I can't help but ask, what has happened to DE CNC? Can someone tell me why we are not seeing this star in outburst. I have searched the internet and can find very little useful information. Could it be a UGWZ?

Kind regards

Stephen [HSP]

DE Cnc
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A good question.  There are only two sources of information I could find - both referenced in VSX and both in German.  Perhaps someone might be good enough to post a translation here please if you think it's worth it?  They are quite short.

I've been following it for many years now.  I seem to recall a note in VSNET years ago mentioning this object (then known as S 10803), which is why I added it to my list.  I'm sure details appeared in Taichi's original e-mail, but unusually for me I have no reference to it at all on my PC.  There must be something to it, otherwise it wouldn't have received it's official VS designation - but is it a CV?

Gary [PYG]

DE Cnc
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I imaged this field at NOFS, in collaboration with Bruce Sumner.  The star identified by Downes as DE Cnc is pretty red; (B-V) = 0.81.  Bruce felt that this was too red, and the identified star was unlikely to be the true DE Cnc, if it is a cataclysmic variable.  Note that the coordinates in Götz's paper are B1950 8:32:33 19:56:36, whereas the VSX/GCVS/Downes coordinates are 08 32 34.86 +19 55 59.9.  However, Götz's chart identification matches the VSX/GCVS/Downes star.  So there is some minor confusion.  There are a few points in the AID and CRTS that seem to indicate outbursts, but pretty infrequent for a U Gem.  There are plenty of visual fainter-thans that would have detected outbursts. I think the jury is still out - more data is needed!  Like most cataclysmics, a detection is worth far more than a fainter-than, so if you have a CCD system, expose long enough to measure the star.

Arne

Gary, I speak German. Do
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Gary,

I speak German. Do you want to pass it on?

Good to see the reds back where they belong. Shame they won't be there come season's end. ;-)

DE Cnc again
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Mati Morel has very kindly translated the 1977 paper written by Gotz.  I've converted to PDF and uloaded to my web site    http://www.garypoyner.pwp.blueyonder.co.uk/DE_Cnc.pdf    Thank you once again Mati!

Mike.  The 1979 paper can be seen here... http://www.sternwarte-sonneberg.de/observatory/images/mvs/volume_08/103.png    but I suspect it's only the first part of it.

As Arne says...The jury is still out!

Mike P again....and Spurs will? ;)

Gary

DE Cnc is not a variable star but an asteroid
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Several years ago I found out that DE Cnc is actually (as expected) an asteroid. I have not published this yet but will try to provide details as soon as possible.

Patrick Schmeer (SPK)

DE Cnc = (588) Achilles
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Here is an excerpt from a private message that I wrote to Dr. Peter Kroll on 2005 January 26:

-----------------------------------------------------------

>The coordinates given were 8h32m33s, +19deg56'.6, 1950.

>Fuer das angegebene Ueberwachungsintervall wurden folgende Erhellungen des Sterns festgestellt:
>
>Datum                      U              B
>1977 Feb. 21      15m.76
>         Mrz.  9                       17m.0
>         Dez.  4                       16.5
>1978 Apr. 25                       16.35
>1979 Feb. 28                       16.78 (2 Platten)
>         Mrz. 23                       17.2  (2 Platten)

According to GUIDE 7.0 on 1977 Feb. 21 at 20h23m UT (588) Achilles was only 28" due south of the above-given catalogued position of DE Cnc. The minor planet was at mag 15.2 and moving at 17"/h due west (PA 271 deg).
Since W. Goetz did not mention both the outbursting object and nearby (588) Achilles I would consider this (main) outburst non-existent (the plate has to be checked - the time of observation, too). For the other dates I could not find any minor planets sufficiently close to DE Cnc. Maybe some of the other brightenings were too close to the limiting magnitude? Or the variable was misidentified?

>Our staff member Alla Zharova identified the star with the USNO A1.0 catalog (8h35m27s.25 +19deg45'30".7 2000).

Other catalogue entries for this star (J2000.0):
GSC 2.2      08h35m27.251s +19o45'30.69" R=17.57  B=18.94
USNO-A2.0  08h35m27.246s +19o45'31.22" R=17.5   B=18.3
2MASS        08h35m27.24s   +19o45'31.4"  J=16.354 H=15.659 K=15.673

So this candidate star is not particularly blue. Of course there could be a CV very close to this star (but I have severe doubts).

Summary:
Maybe there is a variable star at the position of DE Cnc, but in my opinion at least the main outburst did not occur. The other reported brightenings have to be checked.

Patrick Schmeer

DE CNC
pukemaru's picture
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Thanks to all who have replied. Fascinating comments.
Kind regards
Stephen

DE Cnc
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Thanks Patrick.  Unlike you to sit on this without publishing though!

Gary

Re: DE Cnc = (588) Achilles
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In February 2005 Dr. Gerold Richter and Dr. Wolfgang Wenzel confirmed after checking the Sonneberg plates that the object "in outburst" on 1977 February 21 was indeed (588) Achilles.

Patrick

Re: DE Cnc = (588) Achilles
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So, Patrick, does this mean that VSX will be notified that DE Cnc was an asteroid?

Stephen

Re: DE Cnc = (588) Achilles
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Stephen, someone has already added this line:
"P. Schmeer, 2013, AAVSO Forum     Minor planet (588) Achilles."
I'll add more details.

DE Cnc
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As possibly the final word on this subject, Mati Morel has kindly send me a translation of Gotz 1979 paper, which I've uploaded to my web page here...

 http://www.garypoyner.pwp.blueyonder.co.uk/DE_Cnc_2.pdf

Gary [PYG]

AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484