Sky & Telescope - February 2019 - 35

Holy cow,
there it
is - and
blinking with
Dan Gray's
chopper -
WOOHOO!!!

The Crab pulsar,
PSR B0531+21

p LOCATION OF THE PULSAR Left: The 16th-magnitude pulsar, PSR B0531+21, and the very slightly brighter field star that appears next to it, are
exaggerated in brightness in this sketch so they're easily visible. Right: The author's sketch from the night of April 12, 2010, shows how the amplitude of the Crab Pulsar's brightness changed using Dan Gray's "chopper." The minimum to maximum frequency was about 2 seconds as seen using
1210× on the 90-inch Bok telescope at Kitt Peak. The pulsar is the star on the right.

"Holy cow, there it is - and blinking with Dan Gray's chopper
- WOOHOO!!! It was best seen with averted vision and was
quite obvious once I caught the beat of the 2-ish second amplitude. Once I got the beat I watched for about 10 beats before Dan
pushed me away from the eyepiece for his turn. This is a deadsolid awesome sight!"
This observation will always be one of the most exciting
things I've seen through a telescope. My exclamations at the
eyepiece immediately brought all the other observers rushing
to the observing platform as Dan was good-naturedly, but
firmly, pushing me aside for his turn.
I can't say we saw a difference between the primary and
slightly fainter interpulse, but that wasn't the point - we saw
the Crab pulsar's brightness change with our own eyes.

Cool animations
HOWA RD BA NICH (2)

1.
2.

To get an idea of what we saw, check out:
https://is.gd/crabmovie1
See the Crab Nebula expansion over 10 years at:
https://is.gd/crabmovie2
This is a short animation made by Detleff Hartmann using
images he took with his homemade 17.5-inch telescope.

We understood the special nature of this observation, so
everyone took several turns at the eyepiece. We may or may
not be the only ten people to have ever seen the Crab pulsar
change in brightness visually, but we count ourselves exceptionally fortunate to have done so. It's one thing to know that
it rotates at 30 times per second, but it's an utterly breathtaking experience to see that it actually does.

¢ Nearly nine years later Contributing Editor HOWARD BANICH is still enthralled by this observation - he sincerely thanks
his good friend Dan Gray for making the "chopper." Howard
can be reached at hbanich@gmail.com.
+30°

`

Star magnitudes

changes in the pulsar's brightness, the precise rate Dan had
chosen for the shutter made the pulsar smoothly change in
brightness, from maximum to invisibility and back again over
approximately 2 seconds.
It was like a lighthouse beacon on a foggy night:

AURIGA

Elnath

TAURUS
+25°

1
2
3
4
5
6

Crab
Nebula

M1

f

+20° c

Hyades

Aldebaran

+15°

¡
_

a

k1
ORION
5h 30m

k2

5h 00m

4h 30m

sk yandtele scope.com * FE B RUA RY 2 019

35



https://www.is.gd/crabmovie1 https://www.is.gd/crabmovie2 http://www.skyandtelescope.com

Sky & Telescope - February 2019

Table of Contents for the Digital Edition of Sky & Telescope - February 2019

Contents
Sky & Telescope - February 2019 - Cover1
Sky & Telescope - February 2019 - Cover2
Sky & Telescope - February 2019 - 1
Sky & Telescope - February 2019 - Contents
Sky & Telescope - February 2019 - 3
Sky & Telescope - February 2019 - 4
Sky & Telescope - February 2019 - 5
Sky & Telescope - February 2019 - 6
Sky & Telescope - February 2019 - 7
Sky & Telescope - February 2019 - 8
Sky & Telescope - February 2019 - 9
Sky & Telescope - February 2019 - 10
Sky & Telescope - February 2019 - 11
Sky & Telescope - February 2019 - 12
Sky & Telescope - February 2019 - 13
Sky & Telescope - February 2019 - 14
Sky & Telescope - February 2019 - 15
Sky & Telescope - February 2019 - 16
Sky & Telescope - February 2019 - 17
Sky & Telescope - February 2019 - 18
Sky & Telescope - February 2019 - 19
Sky & Telescope - February 2019 - 20
Sky & Telescope - February 2019 - 21
Sky & Telescope - February 2019 - 22
Sky & Telescope - February 2019 - 23
Sky & Telescope - February 2019 - 24
Sky & Telescope - February 2019 - 25
Sky & Telescope - February 2019 - 26
Sky & Telescope - February 2019 - 27
Sky & Telescope - February 2019 - 28
Sky & Telescope - February 2019 - 29
Sky & Telescope - February 2019 - 30
Sky & Telescope - February 2019 - 31
Sky & Telescope - February 2019 - 32
Sky & Telescope - February 2019 - 33
Sky & Telescope - February 2019 - 34
Sky & Telescope - February 2019 - 35
Sky & Telescope - February 2019 - 36
Sky & Telescope - February 2019 - 37
Sky & Telescope - February 2019 - 38
Sky & Telescope - February 2019 - 39
Sky & Telescope - February 2019 - 40
Sky & Telescope - February 2019 - 41
Sky & Telescope - February 2019 - 42
Sky & Telescope - February 2019 - 43
Sky & Telescope - February 2019 - 44
Sky & Telescope - February 2019 - 45
Sky & Telescope - February 2019 - 46
Sky & Telescope - February 2019 - 47
Sky & Telescope - February 2019 - 48
Sky & Telescope - February 2019 - 49
Sky & Telescope - February 2019 - 50
Sky & Telescope - February 2019 - 51
Sky & Telescope - February 2019 - 52
Sky & Telescope - February 2019 - 53
Sky & Telescope - February 2019 - 54
Sky & Telescope - February 2019 - 55
Sky & Telescope - February 2019 - 56
Sky & Telescope - February 2019 - 57
Sky & Telescope - February 2019 - 58
Sky & Telescope - February 2019 - 59
Sky & Telescope - February 2019 - 60
Sky & Telescope - February 2019 - 61
Sky & Telescope - February 2019 - 62
Sky & Telescope - February 2019 - 63
Sky & Telescope - February 2019 - 64
Sky & Telescope - February 2019 - 65
Sky & Telescope - February 2019 - 66
Sky & Telescope - February 2019 - 67
Sky & Telescope - February 2019 - 68
Sky & Telescope - February 2019 - 69
Sky & Telescope - February 2019 - 70
Sky & Telescope - February 2019 - 71
Sky & Telescope - February 2019 - 72
Sky & Telescope - February 2019 - 73
Sky & Telescope - February 2019 - 74
Sky & Telescope - February 2019 - 75
Sky & Telescope - February 2019 - 76
Sky & Telescope - February 2019 - 77
Sky & Telescope - February 2019 - 78
Sky & Telescope - February 2019 - 79
Sky & Telescope - February 2019 - 80
Sky & Telescope - February 2019 - 81
Sky & Telescope - February 2019 - 82
Sky & Telescope - February 2019 - 83
Sky & Telescope - February 2019 - 84
Sky & Telescope - February 2019 - Cover3
Sky & Telescope - February 2019 - Cover4
https://www.nxtbook.com/nxtbooks/aas/st_202406
https://www.nxtbook.com/nxtbooks/aas/st_202405
https://www.nxtbook.com/nxtbooks/aas/st_202404_qr
https://www.nxtbook.com/nxtbooks/aas/st_202404
https://www.nxtbook.com/nxtbooks/aas/st_202403
https://www.nxtbook.com/nxtbooks/aas/st_202402
https://www.nxtbook.com/nxtbooks/aas/st_202401_aus
https://www.nxtbook.com/nxtbooks/aas/st_202401
https://www.nxtbook.com/nxtbooks/aas/st_202312_aus
https://www.nxtbook.com/nxtbooks/aas/st_202312
https://www.nxtbook.com/nxtbooks/aas/st_202311
https://www.nxtbook.com/nxtbooks/aas/st_202310
https://www.nxtbook.com/nxtbooks/aas/st_202309
https://www.nxtbook.com/nxtbooks/aas/st_202308
https://www.nxtbook.com/nxtbooks/aas/st_202307
https://www.nxtbook.com/nxtbooks/aas/st_202306
https://www.nxtbook.com/nxtbooks/aas/st_202305
https://www.nxtbook.com/nxtbooks/aas/st_202304
https://www.nxtbook.com/nxtbooks/aas/st_202304_qr
https://www.nxtbook.com/nxtbooks/aas/st_202303
https://www.nxtbook.com/nxtbooks/aas/st_202302
https://www.nxtbook.com/nxtbooks/aas/st_202301
https://www.nxtbook.com/nxtbooks/aas/st_202212
https://www.nxtbook.com/nxtbooks/aas/st_202211
https://www.nxtbook.com/nxtbooks/aas/st_202210
https://www.nxtbook.com/nxtbooks/aas/st_202209
https://www.nxtbook.com/nxtbooks/aas/st_202208
https://www.nxtbook.com/nxtbooks/aas/st_202207
https://www.nxtbook.com/nxtbooks/aas/st_202206
https://www.nxtbook.com/nxtbooks/aas/st_202205
https://www.nxtbook.com/nxtbooks/aas/st_202204
https://www.nxtbook.com/nxtbooks/aas/st_202203
https://www.nxtbook.com/nxtbooks/aas/st_202202
https://www.nxtbook.com/nxtbooks/aas/st_202201
https://www.nxtbook.com/nxtbooks/aas/st_202112
https://www.nxtbook.com/nxtbooks/aas/st_202111
https://www.nxtbook.com/nxtbooks/aas/st_202110
https://www.nxtbook.com/nxtbooks/aas/st_202109
https://www.nxtbook.com/nxtbooks/aas/st_202108
https://www.nxtbook.com/nxtbooks/aas/st_202107
https://www.nxtbook.com/nxtbooks/aas/st_202106
https://www.nxtbook.com/nxtbooks/aas/st_202105
https://www.nxtbook.com/nxtbooks/aas/st_202104
https://www.nxtbook.com/nxtbooks/aas/st_202103
https://www.nxtbook.com/nxtbooks/aas/st_202102
https://www.nxtbook.com/nxtbooks/aas/st_202101
https://www.nxtbook.com/nxtbooks/aas/skywatch_2021
https://www.nxtbook.com/nxtbooks/aas/st_202012
https://www.nxtbook.com/nxtbooks/aas/st_202011
https://www.nxtbook.com/nxtbooks/aas/st_202010
https://www.nxtbook.com/nxtbooks/aas/st_202009
https://www.nxtbook.com/nxtbooks/aas/st_202008
https://www.nxtbook.com/nxtbooks/aas/st_202007
https://www.nxtbook.com/nxtbooks/aas/st_202006
https://www.nxtbook.com/nxtbooks/aas/st_202005
https://www.nxtbook.com/nxtbooks/aas/st_202004
https://www.nxtbook.com/nxtbooks/aas/st_202003
https://www.nxtbook.com/nxtbooks/aas/st_202002
https://www.nxtbook.com/nxtbooks/aas/st_202001
https://www.nxtbook.com/nxtbooks/aas/st_201912
https://www.nxtbook.com/nxtbooks/aas/st_201911
https://www.nxtbook.com/nxtbooks/aas/st_201910
https://www.nxtbook.com/nxtbooks/aas/st_201909
https://www.nxtbook.com/nxtbooks/aas/st_201908
https://www.nxtbook.com/nxtbooks/aas/st_201907
https://www.nxtbook.com/nxtbooks/aas/st_201906
https://www.nxtbook.com/nxtbooks/aas/st_201905
https://www.nxtbook.com/nxtbooks/aas/st_201904
https://www.nxtbook.com/nxtbooks/aas/st_201903
https://www.nxtbook.com/nxtbooks/aas/st_201902
https://www.nxtbook.com/nxtbooks/aas/st_201901
https://www.nxtbook.com/nxtbooks/aas/st_201812
https://www.nxtbook.com/nxtbooks/aas/st_201811
https://www.nxtbook.com/nxtbooks/aas/st_201810
https://www.nxtbook.com/nxtbooks/aas/st_201809
https://www.nxtbook.com/nxtbooks/aas/st_201808
https://www.nxtbook.com/nxtbooks/aas/st_201807
https://www.nxtbook.com/nxtbooks/aas/st_201806
https://www.nxtbook.com/nxtbooks/aas/st_201805
https://www.nxtbook.com/nxtbooks/aas/st_201804
https://www.nxtbook.com/nxtbooks/aas/st_201803
https://www.nxtbook.com/nxtbooks/aas/st_201802
https://www.nxtbook.com/nxtbooks/aas/st_201801
https://www.nxtbook.com/nxtbooks/aas/st_201712
https://www.nxtbook.com/nxtbooks/aas/st_201711
https://www.nxtbook.com/nxtbooks/aas/st_201710
https://www.nxtbook.com/nxtbooks/aas/st_201709
https://www.nxtbook.com/nxtbooks/aas/st_201708
https://www.nxtbook.com/nxtbooks/aas/st_201707
https://www.nxtbook.com/nxtbooks/aas/st_201706
https://www.nxtbook.com/nxtbooks/aas/st_201705
https://www.nxtbook.com/nxtbooks/aas/st_201704
https://www.nxtbook.com/nxtbooks/aas/st_201703
https://www.nxtbook.com/nxtbooks/aas/st_201702
https://www.nxtbook.com/nxtbooks/aas/st_201701
https://www.nxtbook.com/nxtbooks/aas/st_201612
https://www.nxtbook.com/nxtbooks/aas/st_201611
https://www.nxtbook.com/nxtbooks/aas/st_201610
https://www.nxtbook.com/nxtbooks/aas/st_201609
https://www.nxtbook.com/nxtbooks/aas/st_201608
https://www.nxtbook.com/nxtbooks/aas/st_201607
https://www.nxtbook.com/nxtbooks/aas/st_201606
https://www.nxtbook.com/nxtbooks/aas/st_201605
https://www.nxtbook.com/nxtbooks/aas/st_201604
https://www.nxtbook.com/nxtbooks/aas/st_201603
https://www.nxtbook.com/nxtbooks/aas/st_201602
https://www.nxtbook.com/nxtbooks/aas/st_201601
https://www.nxtbook.com/nxtbooks/aas/st_201512
https://www.nxtbook.com/nxtbooks/aas/st_201511
https://www.nxtbook.com/nxtbooks/aas/st_201510
https://www.nxtbook.com/nxtbooks/aas/st_201509
https://www.nxtbook.com/nxtbooks/aas/st_201508
https://www.nxtbook.com/nxtbooks/aas/st_201507
https://www.nxtbook.com/nxtbooks/aas/st_201506
https://www.nxtbook.com/nxtbooks/aas/st_201505
https://www.nxtbook.com/nxtbooks/aas/st_201504
https://www.nxtbook.com/nxtbooks/aas/st_201503
https://www.nxtbook.com/nxtbooks/aas/st_201502
https://www.nxtbook.com/nxtbooks/aas/st_201501
https://www.nxtbook.com/nxtbooks/aas/st_201412
https://www.nxtbook.com/nxtbooks/aas/st_201411
https://www.nxtbook.com/nxtbooks/aas/st_201410
https://www.nxtbook.com/nxtbooks/aas/st_201409
https://www.nxtbook.com/nxtbooks/aas/st_201408
https://www.nxtbook.com/nxtbooks/aas/st_201407
https://www.nxtbook.com/nxtbooks/aas/st_201406
https://www.nxtbook.com/nxtbooks/aas/st_mars
https://www.nxtbook.com/nxtbooks/aas/st_201405
https://www.nxtbook.com/nxtbooks/aas/st_201404
https://www.nxtbook.com/nxtbooks/aas/st_201403
https://www.nxtbook.com/nxtbooks/aas/st_201402
https://www.nxtbook.com/nxtbooks/aas/st_201401
https://www.nxtbook.com/nxtbooks/aas/st_201312
https://www.nxtbook.com/nxtbooks/aas/st_201311
https://www.nxtbook.com/nxtbooks/aas/st_201310
https://www.nxtbook.com/nxtbooks/aas/st_201309
https://www.nxtbook.com/nxtbooks/aas/st_201308
https://www.nxtbook.com/nxtbooks/aas/st_201307
https://www.nxtbook.com/nxtbooks/aas/st_201306
https://www.nxtbook.com/nxtbooks/aas/st_201305
https://www.nxtbook.com/nxtbooks/aas/st_201304
https://www.nxtbook.com/nxtbooks/aas/st_201303
https://www.nxtbook.com/nxtbooks/aas/st_201302
https://www.nxtbook.com/nxtbooks/aas/st_201301
https://www.nxtbook.com/nxtbooks/aas/st_201212
https://www.nxtbook.com/nxtbooks/aas/st_201211
https://www.nxtbook.com/nxtbooks/aas/st_201210
https://www.nxtbook.com/nxtbooks/aas/st_201209
https://www.nxtbook.com/nxtbooks/aas/st_201208
https://www.nxtbook.com/nxtbooks/aas/st_201207
https://www.nxtbook.com/nxtbooks/aas/st_201206
https://www.nxtbook.com/nxtbooks/aas/st_201205
https://www.nxtbook.com/nxtbooks/aas/st_201204
https://www.nxtbook.com/nxtbooks/aas/st_201203
https://www.nxtbook.com/nxtbooks/aas/st_201202
https://www.nxtbook.com/nxtbooks/aas/st_201201
https://www.nxtbook.com/nxtbooks/aas/st_201112
https://www.nxtbook.com/nxtbooks/aas/st_201111
https://www.nxtbook.com/nxtbooks/aas/st_201110
https://www.nxtbook.com/nxtbooks/aas/st_201109
https://www.nxtbook.com/nxtbooks/aas/st_201108
https://www.nxtbook.com/nxtbooks/aas/st_201107
https://www.nxtbook.com/nxtbooks/aas/st_201106
https://www.nxtbook.com/nxtbooks/aas/st_201105
https://www.nxtbook.com/nxtbooks/aas/st_201104
https://www.nxtbook.com/nxtbooks/aas/st_201103
https://www.nxtbook.com/nxtbooks/aas/st_201102
https://www.nxtbook.com/nxtbooks/aas/st_201101
https://www.nxtbook.com/nxtbooks/aas/st_201012
https://www.nxtbook.com/nxtbooks/aas/st_201011
https://www.nxtbook.com/nxtbooks/aas/st_201010
https://www.nxtbook.com/nxtbooks/aas/st_201009
https://www.nxtbook.com/nxtbooks/aas/st_201008
https://www.nxtbook.com/nxtbooks/aas/st_201007
https://www.nxtbook.com/nxtbooks/aas/st_201006
https://www.nxtbook.com/nxtbooks/aas/st_201005
https://www.nxtbook.com/nxtbooks/aas/st_201004
https://www.nxtbook.com/nxtbooks/aas/st_201003
https://www.nxtbook.com/nxtbooks/aas/st_201002
https://www.nxtbook.com/nxtbooks/aas/st_201001
https://www.nxtbookmedia.com