Magnitude obs for tonight ISS passes ?

[Vega]

Following on from a previous post about the brightness of the ISS I thought it would be interesting to have some observations on what magnitude members think the ISS is on tonights 2 UK passes.

Since the new truss/solar arrays were attached it is considerably brighter IMO. I hope to observe the 2nd, later pass aswell at around 11:20 as the 9:45 pass will still be in a lightish sky which I find affects how bright it 'seems'. The 2nd pass will dim then dissapear before it reaches Pegasus in the East as it goes in to shadow. I guess Jupiter is the only candidate qualifying as a magnitude comparison object.

The more that contribute the better

Vega

[Vega]

.....hello {huge echo... tumbleweed rolls by the thread}

Well ok... my obs is about -2.8

{Gets spooked by the silence and legs it}

Vega

[Greg]

Any good to you..

9 Aug 2.2 22:30:25 10 W 22:33:19 72 N 22:35:08 21 E

10 Aug 0.1 00:05:34 10 W 00:06:28 18 W 00:06:28 18 W

10 Aug -2.3 21:17:56 10 W 21:20:51 82 N 21:23:46 10 E

10 Aug -2.4 22:53:06 10 W 22:56:00 86 N 22:56:35 54 E

11 Aug -2.1 21:40:37 10 W 21:43:31 72 N 21:46:26 10 E

11 Aug -1.6 23:15:45 10 W 23:18:01 45 WSW 23:18:01 45 WSW

[Vega]

Any good to you..

9 Aug 2.2 22:30:25 10 W 22:33:19 72 N 22:35:08 21 E

10 Aug 0.1 00:05:34 10 W 00:06:28 18 W 00:06:28 18 W

10 Aug -2.3 21:17:56 10 W 21:20:51 82 N 21:23:46 10 E

10 Aug -2.4 22:53:06 10 W 22:56:00 86 N 22:56:35 54 E

11 Aug -2.1 21:40:37 10 W 21:43:31 72 N 21:46:26 10 E

11 Aug -1.6 23:15:45 10 W 23:18:01 45 WSW 23:18:01 45 WSW

Not really... was hoping for a more 'amateur' view (ie not based on mass/angles/calculations) on the suggested magnitude of the ISS

[dogfish]

Hi Vega

Sorry, I did see you're original post, but as no one replied I forgot to follow-up. I did reply to Steve's thread (see here http://stargazerslounge.com/index.php?topic=15870.msg163712#msg163712) and posted my inept magnitude assessment (guess) there. I noted that heavens above were saying something in the region of

-2.something mag, but the pass on the Tuesday night did seem a lot brighter to me and certainly brighter than the two passes I saw last night, but then I do not consider myself to be expert competent in such assessments.

Cheers, Martin

[Astroman]

Vega,

The supplied print-out is straight from Heavens-Above. It shows, L-R Date, Magnitude, Appearence time, Appearence altitude, Direction, Peak alt. time, Peak Alt., Exit time, Exit Alt., and Direction. Nothing about telemetry is noted.

[Vega]

I realise that... but I'm sure that might be how the stated magnitude is predicted

[Astroman]

Well no, not really. The mass/angle calculations are how they figure the orbit and whether it will go over your house and by how much. The magnitude would be calc'd by the Sun angle, size and distance of the object and other considerations. Heavens-Above does a decent job, but can't be everywhere, so their estimates can be off by a good factor. Since the attitude of the station changes with respect to the ground path, it's tough to say what the reflective profile will be at any given moment. I think it's a great idea to estimate the brightness you actually see, as compared to background stars. This is the exact principal behind variable star estimates. Go for it!