How to Use a Computerized Telescope: Practical Amateur Astronomy Volume 1

by Michael A. Covington

• ISBN13: 9780521007900
• ISBN10: 0521007909
• Format: Paperback
• Copyright: 2002-11-04
• Publisher: Cambridge University Press
• More Book Details
• Purchase Benefits

Summary

How to Use a Computerized Telescope is the first handbook that describes how to get your computerized telescope up and running, and how to embark on a program of observation. It explains in detail how the sky moves, how your telescope tracks it, and how to get the most out of any computerized telescope. Packed full of practical advice and tips for troubleshooting, it translates the manufacturers' technical jargon into easy-to-follow, step-by-step instructions, and includes many of the author's tried and tested observing techniques. Early chapters explain how to test your telescope's optics, choose eyepieces and accessories, and diagnose operational problems. The second half of the book then gives detailed instructions for three classic telescopes: the Meade LX200, Celestron NexStar 5 and 8, and Meade Autostar (ETX and LX90). Concentrating mainly on telescope operation and troubleshooting, it is the ideal companion to Celestial Objects for Modern Telescopes, also by Michael Covington.

Table of Contents

Preface	xv
Part I Telescopes in general	1	(130)
Welcome to amateur astronomy!	3	(3)
Using a telescope	3	(1)
Learning the sky	4	(1)
Is a computerized telescope right for you?	4	(1)
Material you can skip	5	(1)
Does this book cover your telescope?	5	(1)
How the sky moves	6	(13)
Daily motion	6	(2)
Coordinates	8	(4)
Right ascension and declination	8	(1)
Declination and latitude	9	(1)
Some terminology	10	(1)
Other coordinate systems	10	(1)
Degrees, minutes, and seconds	11	(1)
Distance between points in the sky	12	(1)
Annual motion	12	(1)
Why time of year matters	12	(1)
Sidereal time	13	(1)
Time of day	13	(4)
Solar time and time zones	13	(2)
Hints on using UT	15	(2)
UTC, ET, and other subtleties	17	(1)
Slow changes in R.A. and declination	17	(2)
Precession and epochs	17	(1)
How precession works	17	(1)
Proper motion	18	(1)
How telescopes track the stars	19	(20)
What's inside a computerized telescope	19	(2)
Computer	19	(1)
Motors	20	(1)
Encoders	21	(1)
Digital setting circles (DSC)	21	(1)
Altazimuth and equatorial mounts	21	(1)
Site information	22	(3)
Why it's needed	22	(1)
Obtaining site data	23	(2)
Why compasses don't point north	25	(2)
Setting up the telescope	27	(1)
Choosing alignment stars	28	(1)
Automatic setup with GPS	29	(1)
Tripods and piers	29	(3)
Steadiness	29	(1)
Other tripod and wedge hints	30	(1)
Observatories and permanent piers	31	(1)
Pointing accuracy	32	(4)
What to expect	32	(1)
Factors that affect pointing accuracy	32	(2)
Aligning the telescope tube in the mount	34	(1)
The double-GO TO trick	34	(1)
Meade high-precision mode	35	(1)
TPoint Software	35	(1)
What the telescope is calculating	35	(1)
Computer control	36	(1)
Electricity for telescopes	37	(2)
Using equatorial mounts and wedges	39	(20)
Why equatorial?	39	(1)
Must field rotation be eliminated?	39	(4)
Using an equatorial mount	43	(5)
Setting up the mount	43	(1)
Rough polar-axis alignment without sighting stars	43	(1)
Finding Polaris	44	(1)
Rough polar-axis alignment on Polaris	45	(2)
Initializing the computer	47	(1)
Refining the polar alignment	48	(1)
Iterating on Polaris and one other star	48	(1)
Fine alignment -- the drift method	49	(1)
Using wedges	49	(2)
Tracking in equatorial mode	51	(2)
Tracking rates	51	(2)
Periodic-error correction (PEC)	53	(1)
Setting circles	53	(2)
Southern declination limits	55	(1)
German equatorial mounts	56	(3)
Telescope optics	59	(20)
How a telescope works	59	(1)
Upside down and backward images	59	(2)
Light grasp and image brightness	61	(2)
Resolving power	63	(1)
Types of telescopes	64	(6)
Refractors, reflectors, and catadioptrics	64	(2)
Catadioptric quirks	66	(1)
``Fast'' and ``slow'' f-ratios	67	(1)
Does the central obstruction ruin the image?	68	(1)
Which design is best?	69	(1)
Collimation	70	(4)
Collimating a Schmidt-Cassegrain	70	(3)
Collimating a Newtonian	73	(1)
How often?	74	(1)
Star testing	74	(3)
Buying a telescope secondhand	77	(1)
Cleaning optics	78	(1)
Lenses	78	(1)
Mirrors	78	(1)
Eyepieces and optical accessories	79	(20)
What eyepieces do you need?	79	(1)
Barrel size	79	(1)
Field of view	80	(3)
Measuring field of view	82	(1)
Eye relief	83	(1)
Eyepiece designs	83	(2)
New-generation eyepieces	85	(1)
Anti-reflection coatings	86	(1)
Choosing eyepieces wisely	86	(1)
Eyepiece calculations and technical details	87	(3)
The exit pupil	87	(1)
Limits on low power	88	(1)
Limits on high power	89	(1)
Field stop and tube size	89	(1)
Eyepiece accessories	90	(6)
Diagonals	90	(2)
Barlow lenses	92	(1)
Focal reducers (compressors)	93	(1)
Filters	94	(2)
Eyeglasses	96	(1)
Finders	97	(2)
Astrophotography	99	(23)
Overview	99	(1)
Attaching cameras to telescopes	100	(3)
Optical configurations	100	(2)
Brackets and adapters	102	(1)
Two simple projects to get you started	103	(4)
Project #1: the Moon, afocal method	103	(1)
Project #2: the stars, piggybacking	103	(4)
Equipment for astrophotography	107	(4)
Telescope requirements	107	(1)
35-mm SLR cameras	107	(2)
Other film cameras	109	(1)
Digital and video cameras	109	(1)
Astronomical CCD cameras	110	(1)
Focal length, image size, and f-ratio	111	(4)
Finding the effective focal length	111	(1)
Image size and field of view	112	(1)
Finding the f-ratio	113	(1)
Exposure, film, and development	113	(2)
Focusing and sharpness	115	(1)
Deep-sky techniques	116	(3)
Digital image processing	119	(3)
Troubleshooting	122	(9)
Electrical and computer problems	122	(1)
Keypad problems	123	(2)
Motor and slewing problems	125	(4)
Optical problems	129	(2)
Part II Three classic telescopes	131	(88)
Three that led the revolution	133	(1)
Meade LX200	134	(35)
Introduction	134	(2)
Evaluation of the LX200	134	(1)
Related products	135	(1)
Firmware versions	135	(1)
LX200 websites	136	(1)
Electrical requirements	136	(1)
Keypad	137	(1)
Direction of movement	138	(1)
How to enter negative numbers	138	(1)
Operation without electricity	138	(1)
Motorized operation without alignment	139	(1)
Controlling the slewing speed	140	(1)
Entering date, time, and site information	140	(3)
Setting the time	140	(1)
Setting the date	141	(1)
Entering site latitude and longitude	141	(2)
Aligning the telescope on the sky	143	(6)
Altazimuth mode	143	(3)
Equatorial mode	146	(3)
Finding objects by coordinates	149	(1)
Slewing to a given R.A. and declination	149	(1)
Slewing to a given altitude and azimuth	149	(1)
Dealing with decimal minutes	149	(1)
How to interrupt a slewing movement	150	(1)
Finding deep-sky objects using the built-in catalogues	150	(1)
M (Messier) Catalogue	150	(1)
NGC, IC, and UGC	150	(1)
Finding stars using the built-in catalogues	151	(2)
Named stars	151	(1)
STAR, SAO, and GCVS numbers	152	(1)
Finding the Moon and planets	153	(1)
More precise pointing	154	(3)
How to sync on an object	154	(2)
High-precision mode	156	(1)
Training the Smart Drive (PEC)	157	(1)
Cables, connections, and ports	158	(4)
Keypad and declination cables	158	(1)
CCD port	159	(1)
The serial ports	159	(2)
Other connectors	161	(1)
Internal battery	161	(1)
The floating ground	161	(1)
Known firmware bugs	162	(1)
Mechanical and electrical improvements	162	(1)
Menu maps	163	(6)
Celestron NexStar 5 and 8	169	(24)
Introduction	169	(2)
Related products	169	(1)
Evaluation of the NexStar 5	169	(1)
Firmware versions	170	(1)
NexStar websites	170	(1)
Important precautions	171	(1)
Electrical requirements	171	(1)
Keypad	172	(1)
Direction of movement	172	(1)
How to enter declinations and latitudes	173	(1)
Basic operation without alignment	173	(2)
Operation without electricity	173	(1)
Motorized operation without alignment	174	(1)
Controlling the slewing speed	174	(1)
Entering date, time, and site information	175	(2)
Setting the date and time	175	(1)
Entering site latitude and longitude	176	(1)
Storing an observing site	176	(1)
Aligning the telescope on the sky	177	(5)
Altazimuth mode	177	(4)
Equatorial mode	181	(1)
How to interrupt a slewing movement	182	(1)
Finding objects with the built-in catalogues	183	(1)
Messier, Caldwell, and NGC objects	183	(1)
Stars	183	(1)
Planets	184	(1)
Lists of objects	184	(1)
Sky tours	184	(1)
Finding objects by coordinates	184	(1)
Slewing to a given R.A. and declination	184	(1)
Slewing to a given altitude and azimuth	184	(1)
The ``User Object'' catalogue	184	(1)
More precise pointing	185	(1)
Approaching with and	185	(1)
Backlash adjustment	185	(1)
How to sync on an object	185	(1)
The controversy over tripod leveling	185	(1)
Cables, connections, and ports	186	(1)
Keypad cable	186	(1)
Serial (RS-232) port	186	(1)
Known firmware bugs	187	(1)
Menu maps	187	(6)
Meade Autostar (ETX and LX90)	193	(26)
Introduction	193	(2)
Related products	193	(1)
Evaluation of the Autostar (ETX-90 and LX90)	194	(1)
Firmware versions	194	(1)
Autostar websites	195	(1)
Electrical requirements	195	(1)
Keypad	195	(2)
Is the computer included?	195	(1)
Please type slowly!	196	(1)
How to enter information	196	(1)
Display adjustments	197	(1)
Direction of movement	197	(1)
Display modes	197	(1)
Power-on sequence, date, and time	197	(2)
Entering site information	199	(1)
Choosing your location from a menu	199	(1)
Entering latitude, longitude, and time zone directly	200	(1)
Basic operation without alignment	200	(1)
Operation without electricity	200	(1)
Land mode	201	(1)
Controlling the slewing speed	201	(1)
Aligning the telescope on the sky	201	(4)
Checking the finder	201	(1)
Altazimuth mode	201	(3)
Equatorial mode	204	(1)
How to interrupt a slewing movement	205	(1)
Finding objects with the built-in catalogues	205	(1)
Finding objects by coordinates	205	(1)
More precise pointing	206	(1)
How to sync on an object	206	(1)
High-precision mode	206	(1)
Square spiral search (``box scan'')	206	(1)
Drive training and backlash adjustment	207	(1)
Cables, connections, and ports	207	(1)
The connector panel	207	(1)
The serial port	208	(1)
Upgrading the firmware and downloading data	208	(1)
Other advanced features	209	(2)
Satellite tracking	209	(2)
Sky tours	211	(1)
Menu maps	211	(8)
Index	219