Determination of Rot. Axis Project

From: Bart De Pontieu <BDP_at_MPE.MPE-GARCHING.MPG.DE>
Date: Fri, 28 Apr 1995 16:01:30 -0400
Walter Nissen wrote in seesat/310 :

>No doubt this is an extremely modest start, but I did think it worthwhile
>to announce to the whole list that DRA reports have begun.

Indeed, and thanks to Walter Nissen, Bj"orn Gimle and Mike McCants for
their observations received in the last week. So far we have multiple
timings of the following objects :

April 15, 85- 41 B (#15752), 4 timings by Walter
April 19, 95-  2 D (#23466), 36 timings by Mike
April 21, 95-  2 D (#23466), 38 timings by Mike
April 21, 92-  8 B (#21876), 16 timings by Bj"orn
April 21, 93- 59 B (#22803), 6 timings by Bj"orn

Except for Mike's timings of 95- 2 D the data for the other satellites
is insufficient to draw any conclusions. So, I would appreciate more data
of these objects. I know conditions may not be right for making long obser-
vations for some of you, but we *do* maximalize our chances of determining
the rotation axis if we have lots of timings.
Data for 95-  2 D and all the other objects on our list is of course also
still welcome :

94- 61 B, C1 Kosmos 2292, #23279
94- 45 B, C1 Kosmos 2285, #23190
94- 41 B, C1 Nadezhda 4, #23180
94- 24 B, C1 Kosmos 2279, #23093
92- 73 B, C1 Kosmos 2218, #22208
92- 64 A, Freja, #22161
92- 38 B, SAMPEX Scout rocket, #22013
90- 36 B, C1 Kosmos 2074, #20578
90- 23 B, C1 Kosmos 2061, #20528
87- 74 G, F2 Tsyklon Kosmos 1875-1880, #18340
86- 37 B, C1 Kosmos 1745, #16728
84-109 B, C1 Kosmos 1605, #15360
83- 69 J, C1 Kosmos 1473-1480, #14179
82- 40 J, C1 Kosmos 1357-1364, #13168
70-106 B, Delta/CEP 1 NOAA 1, #4794

>I would have
>liked to have recorded the secondary maxima, i.e., A'a'A'.

You can record them *and* report them, as long as you indicate that they
are secondary maxima. I may (or may not) use them in my analysis later on.
Usually secundary maxima make the results worse, since they are (I think)
caused by flashes of the ends of the cylinder. The software does not
handle flashes on the sides.

In fact in this case timings of the secondary maxima may have helped me
in deciding what 'index' the flashes you saw had.
I may be interpreting too much here (but I know Walter will stop me if I
do that :-), but wouldn't the following indices (indicated with 'BDP')
be closer to reality?

Time    WN  BDP
  0.00  0   0
 20.36  1   1
 68.45  2   3
114.67  3   5
164.85  4   7

This gives a flash period of about 23 seconds. It appears I have not
explained well what the index should convey. I hope this example clarifies
things a bit?

By the way, Bj"orn remarked the following :

>To reduce the risk of transcription errors, I would
>prefer to report the flash times as actual seconds reading on the
>stopwatch,
>and the actual time of the last full minute on the stopwatch before the
>time of first observation, i.e.
>   21   21   27 25.0   16
> 58.75  0
> 73.00  1 ....
>instead of
>   21   21   28 23.75  16
>  0.00  0
> 14.25  1 ....

I agree with this completely, the software does allow for entries in that
format.

For those of you who have tuned into seesat later and have no idea what
DRA is all about, you can read more about it in message 290. Send a
message with Subject: archive get latest/290
to SeeSat-L-request@iris01.plasma.mpe-garching.mpg.de

>(Nor does it bother me one whit that this OBS turns out to correlate
>poorly with the data in the latest Flash.  Too bad.  I saw what I saw and

Actually, I think your observation of 23 seconds *does* correspond well
with the data in the latest Flash. Mike McCants measured 17.3 seconds on
January 15. A rise to 23 s does not appear to be 'out-of-this-world' ;-)
So, it's good that you decided to record what you saw, and not what the
data in Flash suggested to you.

>But I am generally unconcerned about being polluted by
>foreknowledge, as, e.g., AAVSO is.

It seems to me that variable star observing can be more influenced
by 'fore-knowledge' than flash timings.

Cheers,
  Bart
Received on Fri Apr 28 1995 - 15:36:46 UTC

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