Last updated: 8 November 2006
Subject: How to track while solar observing Sent: Saturday, October 28, 2006 20:00:31 From: Tom and Klara Collins (email@example.com) I plan to do my first solar observing after reading articles about the November 8th transit of Mars and solar filters in the latest addition of NightSky magazine. I just purchased the Baader Astrosolar Safety film and I am going to make a cell to hold it that firmly attaches to my ETX-125. My question is how to use the scopes tracking ability or sidereal motion to follow the sun? I will be disappointed if you tell me I have to manually follow the sun considering the ETX's amazing night time abilities. Thank you for your help.Mike here: For short periods, you don't need to change from sidereal rate. However, if you do decide you want to change the tracking rate, you could use a "custom" rate of -1 (which is -0.1% but you have to enter in tenths of a percent of sidereal).
From: richard seymour (firstname.lastname@example.org) Lots of ways. (But first: be sure to cover or remove the -viewfinder-, too...) If you are using your usual viewing site, Utilities/PARK the scope and then look through it. If you're lucky, there'll be a landmark you can center on the next time. Center on it -before- powering up, and the scope (after a PARK) will come up already aligned. Then just GOTO Mercury, and touch up your aiming. Mike's value for Setup/Telescope/Tracking Rate/Custom is a little low... it really wants -3 in the usual Meade units. have fun --dick
Subject: How to track while solar observing Sent: Sunday, November 5, 2006 23:28:59 From: Kim Miau Lee (email@example.com) Dick, Do you mean that before starting the next observation, center the parked scope on a landmark? What does this help? Here you stated -3 tracking rate, do we insert -3 to the autostar controller as well or in percentage, 0.03%? I am confused. -- -K.M. Lee My Astronomy Blog- www.AstronomyNotes.net
From: richard seymour (firstname.lastname@example.org) >> Do you mean that before starting the next observation, center the >> parked scope on a landmark? What does this help? The full sequence is: at the end of one session, PARK. Now note carefully (by looking through the eyepiece) where the scope ends up pointed. (in my case, it's a particular brick on a neighbor's chimney). If you're alt/az, that's due true north, with level optical barrel. The -next- time, set up the tripod exactly as before (i use a 6 inch "torpedo" level to guarantee a level surface), and point the scope at that same "brick". Clamp the clamps and power it up. You've now accomplished two things: (a) the scope thinks it's still aligned, because it was parked. (b) the landmark assures that it -is- still truly aligned, since you're following the basic "how to align" (without LNT) to the letter: barrel level, pointed due true north. Try it... try it at night (you can set up, align as per usual, view a few stars to verify the quality of alignment, PARK, power cycle (it'll still be pointed at the "brick") and see how well it remains aligned by checking against the same stars. Make your own judgements. >> Here you stated -3 tracking rate, do we insert -3 to the autostar >> controller as well or in percentage, 0.03%? I am confused. Under Setup/Telescope/Tracking Rate/Custom enter the value -3 [enter] (you can change the sign by using the left slew key to move the cursor to that position, then the scroll up/down key changes the sign). That's the -only- place you change anything to track at solar rate. (the above assumes you have -not- installed my patch kit with changes the Custom prompt from "enter rate adjustment" to ".01%'s sidereal" ... if you -have- installed my kit, then the proper value is -35 (<-- only with my kit installed!!!)) have fun --dick
I get you about the tracking rate. If I set 35 with your patch kit, does it mean 3.5 in my current autostar controller? Does your patch kit work for autostar #497? Thanks for your tips to park the scope and quickly restore the sequence. I would like to thank Weasner as well for delivering my questions to dick.
> Does your patch kit work for autostar #497? The patch kits you will find at Mike's site work with the 497. (but i would -not- recommend trying to install one this close to the event you're planning to chase...) Go with what works -now-. > I get you about the tracking rate. If I set 35 with your patch kit, does > it mean 3.5 in my current autostar controller? Yes, with the caveat that you cannot enter "3.5" to the normal Autostar (at least with the meaning you need). You can enter 3 or 4, but not 3.5. Background: The Custom Tracking Rate adjustment accepts a 3-digit number, from 999 to -999 on the screen. (note lack of decimal point). That number is in "units" of tenths of percent of sidereal. So "+25" on the screen really means "track at a rate of sidereal + 2.5%" (or 102.5% of sidereal, or 1.025 time sidereal, however you'd like to express it.). So +999 means "add 99.9% of sidereal to sidereal, yielding about 2x sidereal" and -999 means "subtract 99.9% from sidereal, which pretty much stops it". The Sun moves 0.35% slower than sidereal. So in "Meade speak" you'd be choosing between entering -3 and -4 (since you can't enter minus-three-and-a-half). (and the 0.35% is an average approximation, anyway, but good enough for now). What my patch kit does is let the Custom numbers range from 9999 to -9999, and defines them as "hundredths of a percent of sidereal". So 9999 is seen as 99.99% and it does become possible to enter 0.35% But for the transit just go wtih -3 and an unpatched Autostar. Trust me on this... you will be -much- happier and the difference between patched and unpatch will be -totally- imperceptible. Play with patching -after- the event. have fun --dick
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