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Re: Star - Star Observations
From: Brad Morris
Date: 2010 Mar 11, 10:50 -0500
From: Brad Morris
Date: 2010 Mar 11, 10:50 -0500
This didn't take long. 1) Skyscout Right Ascension values are defective by small, but significant amounts 2) Skyscout Declination values are defective by small, but significant amounts. For example, Sirius is given as -16.7175 (S16d 43.1m), while the USNO provides S16d 44.0m 3) My spreadsheet calculates GHA Aries. I had a defective hourly rate for Aries, yielding GHA Aries which was incorrect by a small, but significant result. It is apparent to me that I will have to get the exact values for the Objects and Aries from the Nautical Almanac day page and not rely upon my Skyscout. I bypassed these three defects, by inserting the correct GHA & Dec for Sirius and Alphard from the USNO into the spreadsheet, instead of computing them. My altitudes are now Sirius 31d 56.8 USNO 31d 56.8 Alphard 31d 51.6 USNO 31d 51.6 Perfect. My altitude corrections are Sirius 1.591m USNO -1.6m (sign convention, not a problem) Alphard 1.596m USNO -1.6m Perfect. Apparent distance should then be using Corner Cosines, I get an apparent distance of 40d 21m 24.68s Using Young's formula, I get an apparent distance of 40d 24m 22.05s This yields a difference of 0d 2m 57.37s. Back to my original inquiry, which one provides the more accurate answer? Is it Young's or is it the Corner Cosine method. Best Regards Brad "Confidentiality and Privilege Notice The information transmitted by this electronic mail (and any attachments) is being sent by or on behalf of Tactronics; it is intended for the exclusive use of the addressee named above and may constitute information that is privileged or confidential or otherwise legally exempt from disclosure. If you are not the addressee or an employee or agent responsible for delivering this message to same, you are not authorized to retain, read, copy or disseminate this electronic mail (or any attachments) or any part thereof. If you have received this electronic mail (and any attachments) in error, please call us immediately and send written confirmation that same has been deleted from your system. Thank you."