ASTR 3130 Pre-Lab 1
Directions: Complete the following exercises before you come to the observatory to compete
Lab 1. Bringing the required materials for observing and this completed pre-lab will grant you
access to the telescope. If you have any questions feel free to contact either Dylan or Matt.
1) Given a telescope with Diameter D, and focal length ft, what is the f-ratio (a.k.a. f-number) of
the telescope? If you are observing with an eyepiece with focal length fe, then what is the
magnification of the telescope?
2) Measuring time
a) What is the offset between Eastern Standard Time (EST) and
i) Universal Time (UT)?
ii) Local Sidereal Time (LST) for the week of this lab?
b) Approximately what LSTs correspond to Evening Astronomical Twilight and Midnight
the week of this lab?
3) Choosing Targets
a) How do you convert from Right Ascension (RA) to Hour Angle (HA)?
b) What RAs will be observable between Evening Astronomical Twilight and Midnight the
week of this lab (Consider only -6<HA<+6 as “observable”)?
c) What declinations are available from Leander McCormick Observatory (LMO)?
Hint: You will need to look up LMO’s latitude.
4) What is the equation for the calculation of standard error? (Note: You might find a number of different equations. Which one will be most
relevant to this lab?)
5) Make a catalogue of Betelgeuse and 2 other bright (<2 magnitude) stars will be easily observable between Evening Astronomical
Twilight and Midnight for this lab using the table on the back. Include the stars’ RA & Declination Coordinates, (V) magnitudes, local
times of transit (in LST and EST), the airmass at transit, and what constellation they are in.
Star
Betelgeuse
RA
Declination
Constellation
Magnitude
Transit (LST)
Transit (EST)
Airmass