Sky and Telescope - September 2018 - 30

MYSTERY OBJECT

T

by David Nakamoto

he Case Opens: A Strange But
Uninteresting Star

Our story begins in the late 1800s. Invented in
1839, photography had advanced enough later in the century to become a new and exciting tool in astronomy. Like
anyone with a new tool, astronomers wanted to explore
what possibilities it offered.
With photography, astronomers could, for the first
time, capture exactly what was visible through the telescope, rather than document their observations through
writing or drawing. They could record stars to much
fainter magnitudes than the eye could see and then take
their time examining the results in the comfort of an
office, even during daylight hours. Photography was also
invaluable for building up a comprehensive and permanent reference for future study. It allowed for complete
and accurate sky surveys, and yielded studies that could
cover years or even decades.
Several observatories, including Harvard College Observatory in the United States and Sonneberg Observatory in
Germany, performed all-sky surveys, beginning in 1885
and 1926, respectively, that led to important discoveries
concerning stellar spectra and classification. These observations were recorded in blackand-white on glass plates that
could be fairly large, typically
measuring 8 by 10 inches or
even up to 14 by 17 inches,
and sometimes contained
tens of thousands of stars.
Photographic plates were
particularly useful in the
study of variable stars - comparing two or more plates
of the same region at different times would render any
variable object readily visible.
Using this method, astronomers at both observatories
started to find thousands of
variable objects.
And so it was that the first part of our detective story
starts. In 1929 German astronomer Cuno Hoffmeister at
Sonneberg Observatory identified what he thought was a
variable star in the small constellation of Lacerta, the Lizard. Following the standard naming convention for variable
stars, it was designated BL Lacertae, or BL Lac for short.
Studies showed that BL Lac fluctuated on relatively
short timescales between magnitudes 13 and 16 but with
no discernible pattern, making it challenging to come up
with a hypothesis to explain the variability.
In 1957 the great tome on variable stars Geschichte und
Literatur der Lichtwechsels des veränderlichen Sterne was pub-

30

S E P TE M B E R 2 018 * SK Y & TELESCOPE

The



Table of Contents for the Digital Edition of Sky and Telescope - September 2018

Contents
Sky and Telescope - September 2018 - Cover1
Sky and Telescope - September 2018 - Cover2
Sky and Telescope - September 2018 - 1
Sky and Telescope - September 2018 - Contents
Sky and Telescope - September 2018 - 3
Sky and Telescope - September 2018 - 4
Sky and Telescope - September 2018 - 5
Sky and Telescope - September 2018 - 6
Sky and Telescope - September 2018 - 7
Sky and Telescope - September 2018 - 8
Sky and Telescope - September 2018 - 9
Sky and Telescope - September 2018 - 10
Sky and Telescope - September 2018 - 11
Sky and Telescope - September 2018 - 12
Sky and Telescope - September 2018 - 13
Sky and Telescope - September 2018 - 14
Sky and Telescope - September 2018 - 15
Sky and Telescope - September 2018 - 16
Sky and Telescope - September 2018 - 17
Sky and Telescope - September 2018 - 18
Sky and Telescope - September 2018 - 19
Sky and Telescope - September 2018 - 20
Sky and Telescope - September 2018 - 21
Sky and Telescope - September 2018 - 22
Sky and Telescope - September 2018 - 23
Sky and Telescope - September 2018 - 24
Sky and Telescope - September 2018 - 25
Sky and Telescope - September 2018 - 26
Sky and Telescope - September 2018 - 27
Sky and Telescope - September 2018 - 28
Sky and Telescope - September 2018 - 29
Sky and Telescope - September 2018 - 30
Sky and Telescope - September 2018 - 31
Sky and Telescope - September 2018 - 32
Sky and Telescope - September 2018 - 33
Sky and Telescope - September 2018 - 34
Sky and Telescope - September 2018 - 35
Sky and Telescope - September 2018 - 36
Sky and Telescope - September 2018 - 37
Sky and Telescope - September 2018 - 38
Sky and Telescope - September 2018 - 39
Sky and Telescope - September 2018 - 40
Sky and Telescope - September 2018 - 41
Sky and Telescope - September 2018 - 42
Sky and Telescope - September 2018 - 43
Sky and Telescope - September 2018 - 44
Sky and Telescope - September 2018 - 45
Sky and Telescope - September 2018 - 46
Sky and Telescope - September 2018 - 47
Sky and Telescope - September 2018 - 48
Sky and Telescope - September 2018 - 49
Sky and Telescope - September 2018 - 50
Sky and Telescope - September 2018 - 51
Sky and Telescope - September 2018 - 52
Sky and Telescope - September 2018 - 53
Sky and Telescope - September 2018 - 54
Sky and Telescope - September 2018 - 55
Sky and Telescope - September 2018 - 56
Sky and Telescope - September 2018 - 57
Sky and Telescope - September 2018 - 58
Sky and Telescope - September 2018 - 59
Sky and Telescope - September 2018 - 60
Sky and Telescope - September 2018 - 61
Sky and Telescope - September 2018 - 62
Sky and Telescope - September 2018 - 63
Sky and Telescope - September 2018 - 64
Sky and Telescope - September 2018 - 65
Sky and Telescope - September 2018 - 66
Sky and Telescope - September 2018 - 67
Sky and Telescope - September 2018 - 68
Sky and Telescope - September 2018 - 69
Sky and Telescope - September 2018 - 70
Sky and Telescope - September 2018 - 71
Sky and Telescope - September 2018 - 72
Sky and Telescope - September 2018 - 73
Sky and Telescope - September 2018 - 74
Sky and Telescope - September 2018 - 75
Sky and Telescope - September 2018 - 76
Sky and Telescope - September 2018 - 77
Sky and Telescope - September 2018 - 78
Sky and Telescope - September 2018 - 79
Sky and Telescope - September 2018 - 80
Sky and Telescope - September 2018 - 81
Sky and Telescope - September 2018 - 82
Sky and Telescope - September 2018 - 83
Sky and Telescope - September 2018 - 84
Sky and Telescope - September 2018 - Cover3
Sky and Telescope - September 2018 - Cover4
http://www.nxtbook.com/nxtbooks/newtrack/st_201811
http://www.nxtbook.com/nxtbooks/newtrack/st_201810
http://www.nxtbook.com/nxtbooks/newtrack/st_201809
http://www.nxtbook.com/nxtbooks/newtrack/st_201808
http://www.nxtbook.com/nxtbooks/newtrack/st_201807
http://www.nxtbook.com/nxtbooks/newtrack/st_201806
http://www.nxtbook.com/nxtbooks/newtrack/st_201805
http://www.nxtbook.com/nxtbooks/newtrack/st_201804
http://www.nxtbook.com/nxtbooks/newtrack/st_201803
http://www.nxtbook.com/nxtbooks/newtrack/st_201802
http://www.nxtbook.com/nxtbooks/newtrack/st_201801
http://www.nxtbook.com/nxtbooks/newtrack/st_201712
http://www.nxtbook.com/nxtbooks/newtrack/st_201711
http://www.nxtbook.com/nxtbooks/newtrack/st_201710
http://www.nxtbook.com/nxtbooks/newtrack/st_201709
http://www.nxtbook.com/nxtbooks/newtrack/st_201708
http://www.nxtbook.com/nxtbooks/newtrack/st_201707
http://www.nxtbook.com/nxtbooks/newtrack/st_201706
http://www.nxtbook.com/nxtbooks/newtrack/st_201705
http://www.nxtbook.com/nxtbooks/newtrack/st_201704
http://www.nxtbook.com/nxtbooks/newtrack/st_201703
http://www.nxtbook.com/nxtbooks/newtrack/st_201702
http://www.nxtbook.com/nxtbooks/newtrack/st_201701
http://www.nxtbook.com/nxtbooks/newtrack/st_201612
http://www.nxtbook.com/nxtbooks/newtrack/st_201611
http://www.nxtbook.com/nxtbooks/newtrack/st_201610
http://www.nxtbook.com/nxtbooks/newtrack/st_201609
http://www.nxtbook.com/nxtbooks/newtrack/st_201608
http://www.nxtbook.com/nxtbooks/newtrack/st_201607
http://www.nxtbook.com/nxtbooks/newtrack/st_201606
http://www.nxtbook.com/nxtbooks/newtrack/st_201605
http://www.nxtbook.com/nxtbooks/newtrack/st_201604
http://www.nxtbook.com/nxtbooks/newtrack/st_201603
http://www.nxtbook.com/nxtbooks/newtrack/st_201602
http://www.nxtbook.com/nxtbooks/newtrack/st_201601
http://www.nxtbook.com/nxtbooks/newtrack/st_201512
http://www.nxtbook.com/nxtbooks/newtrack/st_201511
http://www.nxtbook.com/nxtbooks/newtrack/st_201510
http://www.nxtbook.com/nxtbooks/newtrack/st_201509
http://www.nxtbook.com/nxtbooks/newtrack/st_201508
http://www.nxtbook.com/nxtbooks/newtrack/st_201507
http://www.nxtbook.com/nxtbooks/newtrack/st_201506
http://www.nxtbook.com/nxtbooks/newtrack/st_201505
http://www.nxtbook.com/nxtbooks/newtrack/st_201504
http://www.nxtbook.com/nxtbooks/newtrack/st_201503
http://www.nxtbook.com/nxtbooks/newtrack/st_201502
http://www.nxtbook.com/nxtbooks/newtrack/st_201501
http://www.nxtbook.com/nxtbooks/newtrack/st_201412
http://www.nxtbook.com/nxtbooks/newtrack/st_201411
http://www.nxtbook.com/nxtbooks/newtrack/st_201410
http://www.nxtbook.com/nxtbooks/newtrack/st_201409
http://www.nxtbook.com/nxtbooks/newtrack/st_201408
http://www.nxtbook.com/nxtbooks/newtrack/st_mars
http://www.nxtbook.com/nxtbooks/newtrack/st_201407
http://www.nxtbook.com/nxtbooks/newtrack/st_201406
http://www.nxtbook.com/nxtbooks/newtrack/st_201405
http://www.nxtbook.com/nxtbooks/newtrack/st_201404
http://www.nxtbook.com/nxtbooks/newtrack/st_201403
http://www.nxtbook.com/nxtbooks/newtrack/st_201402
http://www.nxtbook.com/nxtbooks/newtrack/st_201401
http://www.nxtbook.com/nxtbooks/newtrack/st_201312
http://www.nxtbook.com/nxtbooks/newtrack/st_201311
http://www.nxtbook.com/nxtbooks/newtrack/st_201310
http://www.nxtbook.com/nxtbooks/newtrack/st_201309
http://www.nxtbook.com/nxtbooks/newtrack/st_201308
http://www.nxtbook.com/nxtbooks/newtrack/st_201307
http://www.nxtbook.com/nxtbooks/newtrack/st_201306
http://www.nxtbook.com/nxtbooks/newtrack/st_201305
http://www.nxtbook.com/nxtbooks/newtrack/st_201304
http://www.nxtbook.com/nxtbooks/newtrack/st_201303
http://www.nxtbook.com/nxtbooks/newtrack/st_201302
http://www.nxtbook.com/nxtbooks/newtrack/st_201301
http://www.nxtbook.com/nxtbooks/newtrack/st_201212
http://www.nxtbook.com/nxtbooks/newtrack/st_201211
http://www.nxtbook.com/nxtbooks/newtrack/st_201210
http://www.nxtbook.com/nxtbooks/newtrack/st_201209
http://www.nxtbook.com/nxtbooks/newtrack/st_201208
http://www.nxtbook.com/nxtbooks/newtrack/st_201207
http://www.nxtbook.com/nxtbooks/newtrack/st_201206
http://www.nxtbook.com/nxtbooks/newtrack/st_201205
http://www.nxtbook.com/nxtbooks/newtrack/st_201204
http://www.nxtbook.com/nxtbooks/newtrack/st_201203
http://www.nxtbook.com/nxtbooks/newtrack/st_201202
http://www.nxtbook.com/nxtbooks/newtrack/st_201201
http://www.nxtbook.com/nxtbooks/newtrack/st_201112
http://www.nxtbook.com/nxtbooks/newtrack/st_201111
http://www.nxtbook.com/nxtbooks/newtrack/st_201110
http://www.nxtbook.com/nxtbooks/newtrack/st_201109
http://www.nxtbook.com/nxtbooks/newtrack/st_201108
http://www.nxtbook.com/nxtbooks/newtrack/st_201107
http://www.nxtbook.com/nxtbooks/newtrack/st_201106
http://www.nxtbook.com/nxtbooks/newtrack/st_201105
http://www.nxtbook.com/nxtbooks/newtrack/st_201104
http://www.nxtbook.com/nxtbooks/newtrack/st_201103
http://www.nxtbook.com/nxtbooks/newtrack/st_201102
http://www.nxtbook.com/nxtbooks/newtrack/st_201101
http://www.nxtbook.com/nxtbooks/newtrack/st_201012
http://www.nxtbook.com/nxtbooks/newtrack/st_201011
http://www.nxtbook.com/nxtbooks/newtrack/st_201010
http://www.nxtbook.com/nxtbooks/newtrack/st_201009
http://www.nxtbook.com/nxtbooks/newtrack/newtrack_st_201009
http://www.nxtbook.com/nxtbooks/newtrack/st_201008_v2
http://www.nxtbook.com/nxtbooks/newtrack/st_201008
http://www.nxtbook.com/nxtbooks/newtrack/st_201007
http://www.nxtbook.com/nxtbooks/newtrack/st_201005_v2
http://www.nxtbook.com/nxtbooks/newtrack/st_201006
http://www.nxtbook.com/nxtbooks/newtrack/st_201005
http://www.nxtbook.com/nxtbooks/newtrack/st_201004
http://www.nxtbook.com/nxtbooks/newtrack/st_201003v4
http://www.nxtbook.com/nxtbooks/newtrack/st_201003v3
http://www.nxtbook.com/nxtbooks/newtrack/st_201003v2
http://www.nxtbook.com/nxtbooks/newtrack/st_201003
http://www.nxtbook.com/nxtbooks/newtrack/st_201002
http://www.nxtbook.com/nxtbooks/newtrack/st_201001
http://www.nxtbookMEDIA.com