At the Equator

[Rajeev]

Hi

 

I am moving to 1^o below the equator - so virtually on the equator.

I plan to buy a GEM, possibly the Losmandy GM8 mount. I need to know the following before buying:

 

1. Does an equatorial mount work on the equator.

2. If yes, how does one polar align on the equator given that none of the celestial poles will be visible from there

3. Is a 'go to' system necessary for observing from the equator

 

Anything else I should consider before buying. Any accessories I should consider?

 

thanks

Rajeev

[Stub Mandrel]

3 minutes ago, Rajeev said:

Hi

 

I am moving to 1^o below the equator - so virtually on the equator.

I plan to buy a GEM, possibly the Losmandy GM8 mount. I need to know the following before buying:

 

1. Does an equatorial mount work on the equator.

2. If yes, how does one polar align on the equator given that none of the celestial poles will be visible from there

3. Is a 'go to' system necessary for observing from the equator

 

Anything else I should consider before buying. Any accessories I should consider?

 

thanks

Rajeev

1. It theory it does, but in practice you my not be able to 'lie the mount down' enough. The EQ 5 manual says its OK for 28 degrees to 90 degrees on a tripod, but it works at the equator if you put it on a pier (fixed post mount)
2. I've always wondered if you use a spirit level! I imagine you have to use drift alignment.
3. No, you you should be able to use setting circles or star hopping.

[Davey-T]

Are you planning on imaging ? otherwise a fork mount ALT / AZ type of thing works better at aiming straight up and all points between.

I have friend who used to live in British Guyana but he only used to do visual.

Dave

 

[Rajeev]

Only visual

 

[Davey-T]

27 minutes ago, Rajeev said:

Only visual

 

No point complicating the issue with a GEM mount then.

https://www.firstlightoptics.com/cpc-deluxe-hd/cpc925deluxe-1108.html

Dave

[Waldemar]

Alt/Az will do absolutely fine. At your latitude of -1 that is virtually the same as an equatorial mount. So basically you are in luxurious position... year around nice long nights as well...  and good rum, too... boy I envy you!!

In my opinion goto is nice everywhere. A lot less hassle, but not everybody agrees with that...

[ollypenrice]

My first ever encounter with an astronomical telescope was at about one degree south of the equator. 

Alt Az will work fine but, for the record, so will a GEM. Although the stock tripods may not allow you to set up in the usual way by levelling the top of the mount, there is no reason why you should not make a pier with a tilted top sloping so that you can get the polar axis down to horizontal. The angle of the bottom of the mount has absolutely nothing to do with the polar axis or polar alignment. 

Olly

[Cosmic Geoff]

Why do you want a GEM? So far as I can see, there are two reasons for wanting one: firstly to carry out visual observations that require tracking, e.g. when observing a planet at high magnification for an extended period. Secondly for astrophotography.

If the former, you could also use an alt-az GoTo mounting.

There does not seem to be much demand for amateur astronomy equipment in the low latitudes. However there are some equatorial mounts that are designed to work down to the equator, e.g. the AZ-EQ5. If all these look too expensive, the other option is to buy a mass-market GEM mounting (e.g. an EQ-5) new or used, and modify it yourself, typically by removing any bolts, etc that prevent the latitude being set to 0 deg, and then performing the necessary engineering to get the mount head to go to the required position - and stay there. My EQ-5 looks as if it would go to 0 deg with a metal bar and bolt removed, and the weight of mount head and scope would keep it there.  Be aware that the centre of gravity of the heavy stuff will be shifted to one side.

[Stub Mandrel]

21 minutes ago, Cosmic Geoff said:

Why do you want a GEM? So far as I can see, there are two reasons for wanting one: firstly to carry out visual observations that require tracking, e.g. when observing a planet at high magnification for an extended period. Secondly for astrophotography.

If the former, you could also use an alt-az GoTo mounting.

There does not seem to be much demand for amateur astronomy equipment in the low latitudes. However there are some equatorial mounts that are designed to work down to the equator, e.g. the AZ-EQ5. If all these look too expensive, the other option is to buy a mass-market GEM mounting (e.g. an EQ-5) new or used, and modify it yourself, typically by removing any bolts, etc that prevent the latitude being set to 0 deg, and then performing the necessary engineering to get the mount head to go to the required position - and stay there. My EQ-5 looks as if it would go to 0 deg with a metal bar and bolt removed, and the weight of mount head and scope would keep it there.  Be aware that the centre of gravity of the heavy stuff will be shifted to one side.

As long as you don't get taken in by the 'level the mount' myth, you could just fit an equatorial wedge between tripod and EQ mount.

[Cosmic Geoff]

5 hours ago, Stub Mandrel said:

As long as you don't get taken in by the 'level the mount' myth, you could just fit an equatorial wedge between tripod and EQ mount.

It would probably be easier to modify the mount than to fabricate a custom equatorial wedge. Besides, the latitude mechanism on the EQ-5 mount, with its limited movement and its two bendy bolts for restraint and adjustment, is IMHO a piece of rubbish that deserves to be replaced by something better. The only reason they make it that way is to cut cost.