Problem with UTC+9:30

[Lucia (Lucia)]

Hi,

My name is Lucía and I'm a graduate student from La Laguna, Tenerife
(Spain). This June, a group of researches from IAC (Instituto Astrofísico
de Canarias) is going to Darwin to observe the transit of Venus. Right now,
we are testing our mount and telescope, but we found a problem. The mount,
to perfom a good tracking has to take in account the timezone, which for
Darwin is UTC +9:30. We can achieve UTC +9 and UTC +10. We thought of
modifying the UTC time so it will match UTC +9:30. We also thought that you
guys may have encounter the same problem and found a better solution. Can
you help us? We would appreciate it.

[OICURMT]

You will need to provide the type of mount in order for someone to assist you...

[Lucia (Lucia)]

Oh yeah, sorry. The mount is a LosMandy G11.

Thank you

[iceman (Mike)]

I'm not sure how much difference 30 minutes will make in tracking the sun. Does it need to be super accurate?
Will you be able to readjust if it starts drifting a little?

[lepton3 (Ivan)]

Hi Lucia,

I live in Adelaide, which is currently UT+9.5, and UT+10.5 in summer. The fractional timezone is very often a problem with astro equipment.

So, I ignore it and set all my equipment to UT+0.

You may find that your mount only requires the lat and long to perform accurate tracking, and you can just set the timezone to 0 and work in UT (ignore local time).

Good luck.

-Ivan

[Lucia (Lucia)]

Thank you all.

First, Mike. Yes, the tracking has to be accurate, so we are not tracknig the Sun, but Venus. It can only drift about 1 arcmin (better if less). We might readjust, but we are trying to avoid that.

Second, Ivan. Thank you for your suggestion. Will it perform accurate tracking with utc+0?? I'm not sure it will be accurate enough or if its valid, but I wil try it here.

Regards to all,

Lucía

[mithrandir (Andrew)]

Originally Posted by Lucia

Second, Ivan. Thank you for your suggestion. Will it perform accurate tracking with utc+0?? I'm not sure it will be accurate enough or if its valid, but I wil try it here.

Lucia,

The first question should be, can you set your G11 for Darwin's latitude (12°40"S)? Losmandy says:
"The altitude range is from 14° to 64°. If you live at latitudes closer to the poles, you will need the Zero Degree Latitude Adapter which is sold as an optional accessory and increases the latitude range from 0° to 84°."

I have always had my G11+Gemini set to use UTC. It has a StarGPS and that sends UTC. UTC removes any doubt as to what the local time offset should be. (The politicians keep changing when daylight saving starts. I forgot to change the time on my DSLR on Sunday and had to edit the time on all the images I took before I remembered to fix it.)

If you manually set it to local time, the mount has to use the offset to work out UTC, so it is simpler to start with UTC.

As long as the time and location are correct, it just works. It mainly needs the time to work out the location of the alignment stars so it can point the OTA roughtly where the first alignment star is located. If you give it the wrong offset it will just start out by 1 hour wrong in RA for each hour of error.

If you do not have a GPS you can plug into the mount but do have an iPhone, there is a free app called AstroClock that gives you Local, UTC, LST and JD. It probably works on the iPad. There might be an Android version, I haven't looked.

When it comes to tracking, it is more important for the mount to be aligned. You need to be in position well before dawn to have stars with which to align the mount. If you have a night or more before the transit you will have time to check the alignment and get to enjoy the best part of the sky.