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Discovery of AO Tau Discovery of AF Cam


adolfodarriba@
observatoriolascasqueras.es




Castellano Ingles
My last discovery

My last important discovery is referring to the erroneous position of variable AO Tau in charts of the AAVSO, that comes like:

AO Tau
0443+28. Revision 1998 AAVSO. Preliminary. Chart (e)
Magn.- 12.7 - 16.6 p
Period.- 229.2 days
Type - Mira
Spec.- C4.2 - C7.4


The 8 of November of 2,002, with a Celestron C8 of 203 mm in line of vision, I noticed myself that a star of the variable of magnitude 14.3 existed closely together approximately, omitted in the chart of the AAVSO.

To the following morning I called to Jose Ripero so that it verified to me if it could be an asteroid. It communicated to me that it did not appear in the apulsos of asteroids an object in that position, reason why I prepared myself to observe it the following night. There for my surprise, it followed in the same position and same brightness. As we did not know that it could be, I tried it to observe in the third night and again it was there.

Sailing by Internet I was generated an image in DSS of the field of variable AO Tau and there it was the star that saw. It was clear. The chart of the AAVSO had committed an error in not representing a so shining star. Marked like AO Tau (VSNET).


Field of the variable AO Tau


As it is normal, I wanted to resist the chart of the AAVSO with the chart of the VSNET. Again I took a surprise because in the chart of the VSNET it indeed positioned the variable with the star that I discovered. That is to say, now it did not know clearly as of two stars it was the variable, although the chart of the AAVSO omitted one of the two, not being thus in the chart of the VSNET.

The best way in astronomy to know on the matter but, is observing it in all the nights available, thus being able to make a curve of the most trustworthy light possible as it is next.


Light curve AO Tau


In a principle it was clear that the star which I discovered in first nights varied with time, being able to be therefore variable AO Tau, being correct the chart of the VSNET.

The chance was that I had the pleasure to to Hitoshi Yamaoka of the VSNET in the conferences of Valencia where met to great personalities like the Nobel prize Martin Rees. He is when in terrible ingles as for me, I tried to explain my discovery, requesting to him his electronic mail to send all the documentation to him available.

Next I reproduce its answer, with its consent, that I along with sent to Aaron Price of the AAVSO all the observations, the previous image in DSS and two charts of variable AO Tau totally resisted.
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-id/msg00789.html


Dear Adolfo,

Thank you very much for your kindest welcome at Valencia!
The chart AO Tau has error the position.
The most probable identification of AO Tau is:

USNO-A2.004:49:44.583+28:20:29.29r=12.5b=16.0 
2MASS04:49:44.60+28:20:29.4J=7.314H=6.463Ks=5.980

which is about 1' east of the nominal position of AO Tau (4:49:40, +28:20.6 (J2000.0)). The VSNET chart correctly point this star as AO Tau.
The AAVSO chart seems to point the below star as AO Tau errornously;

GSC 1843.12804:49:41.57+28:20:16.4p=14.96  
USNO-A2.004:49:41.575+28:20:16.52r=13.2b=14.9 
2MASS04:49:41.60+28:20:16.5J=12.262H=11.862Ks=11.778

Sincerely, Hitoshi


It is when it appeared SebastiÓ Torrell to explain the subject of photometry to me that is explicit in this answer that I did not know. As the variable is of the Mira type, it has to be itself very red by force.

At the beginning of the discovery, I sent an electronic mail to him to Aaron Price of the AAVSO so that it verified it, but at first it did not take me very in serious. But most peculiar, it is than observations exist from year 1979 without nobody has been noticed of the error. How many useless observations!

But the main discovery is in these two images of but down. As it is appraised in the image of the left, the cross that represents the center of the image does not agree with variable AO Tau. That is to say, after my notification, IAU (International Astronomical Union) and the AAVSO (American Association of Variable Star Observers) rectified the error, recognizing that I had reason. And what is more important, than all star catalogues recognized internationally they will contain this error since in the images in DSS also they commit it.


Before 6-May-2003. Field of the variable AO Tau After 6-May-2003. Field of the variable AO Tau


Finally AAVSO has updated in January of the 2.005: http://charts.aavso.org/charts/TAU/AO_TAU/

Note: I thank to Jose Ripero, Diego Rodriguez, Hitoshi Yamaoka, Teˇfilo Arranz and to SebastiÓ Torrell by the collaboration and verification of this one important discovery. And to all those that have made possible this curve of light. Also to Marc Biesmans to modernize the chart for AAVSO.



LAST COMMENTS

Imagen de Teofilo Arranz


According to the AAVSO, the variable AO Tau descends until the magnitude 16,6. As it is shown in the following picture, carried out by Teˇfilo Arranz, it can have a minimum magnitude of 18,7. it can even descend a lot but. Alone they lack observations that confirm it.


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