vertex angle, TiPS

Walter Nissen (dk058@cleveland.Freenet.Edu)
Wed, 24 Jul 1996 18:53:38 -0400

There seems to be a lack of agreement between surveying and astronomy on 
the name of the angle and the definition (see appendices).  Therefore, I 
suggest this convention.  Assume that the observer is able to distinguish 
Ralph from Norton.  If the orientation is, e.g.: 
 
n         n                                R                            n 
|           \                              |                           / 
|            \          n--------R         |         R---------n      / 
|              \                           |                         / 
|                \                         |                        / 
R                 R                        n                       R 
 
then the vertex angle is: 
 
0           45            90             180             270         330 
 
and the observer should report a vertex angle between 0 and 359.99 
degrees.  I.e., the vertex angle (see appendix) of Norton with respect to 
Ralph.  If the observer cannot distinguish Ralph from Norton, then the 
angle reported should be a vertex angle, determined in the same way, 
between 0 and 179.99 degrees. 
 
Modelled after PPAS, I suggest this format: 
Walter I. Nissen, Jr., CDP, dk058@cleveland.freenet.edu, 55 Barrett RD #808, 
Berea, OH 44017-1657, USA, 216-243-4980, -81d 51.823', 41d 22.413', 256m 
yy-lllpp yy-mm-dd hh:mm:ss.ss NN d->d al v.a UML m1  sp RN mag apur Comments 
96- 29 ? 96-07-11  4:43       WN N->S 50 140?LML 6      xx   7x35  steady angle 
96- 29 ? 96-07-12  3:35       WN N->S 65  45?LML        xx  11x80   TiPS 
96- 29 ? 96-07-12  3:38       WN N->S 40  45?LML        xx  11x80   TiPS 
96- 29 ? 96-07-16  2:39:30    WN N->S 40   0  V  5      xx  11x80   TiPS 
96- 29 ? 96-07-16  2:40:30    WN N->S 30   0  V         xx  11x80   TiPS 
96- 29 ? 96-07-21  2:18:52.08 WN N->S 57 150 LML        xx  11x80   TiPS 
96- 29 ? 96-07-21  2:24:39.53 WN N->S 14 175 LML        xx  11x80   TiPS 
96- 29 ? 96-07-23  1:50:00    WN N->S 58             sp?    11x80   TiPS 
96- 29 ? 96-07-23  1:51:30    WN N->S 46  10 UML        xx  11x80   TiPS 
96- 29 ? 96-07-23  1:53:30    WN N->S 28   5 UML        xx  11x80   TiPS 
 
The pp is the piece number in the COSPAR ID (apparently no agreement yet) 
UTC data and time are given (give local time and zone also if your clocks are 
 not set to UTC, or if you have any doubt about the conversion) 
NN is the observer's initials (from PPAS) 
al is the altitude, if the al's you provide don't suggest the maximum 
  you are encouraged to provide a record to give the max altitude 
d->d is the direction of motion 
v.a is the vertex angle (norton above = 0, norton left = 90, etc.) 
UML is Upper Mass Leading, Lower Mass Leading or Vertical 
m1 is total visual magnitude 
sp is blank if no sparkles are observed, sp if 1-5 are observed, 
  SP if more than 5 are observed 
RN is blank if the orientation could not be observed, xx if Ralph could not 
be distinguished from Norton, and RN if it could. 
mag is image magnification 
apur is aperature in mm 
Comments are encouraged to run into paragraphs if you have things to say 
 
Do we need left->right also? 
Azimuth also? 
Anything else? 
 
The dashes(-) in the date and the colons(:) in the time are an unnecessary 
affectation. 
 
 
Cheers. 
 
Walter Nissen                   dk058@cleveland.freenet.edu 
 
--- 
 
David Dunham writes: 
... vertex angle in occultation predictions ... is measured like 
position angle, but 0 is the local vertical direction, rather than north. 
Hence, 0 deg. is up, 90 is to the left, 180 is down, and 270 is to the 
right. 
 
-- 
 
In 
http://www.auslig.gov.au/geodesy/astro/definiti.htm - size 8K 
we find this: 
 
AUSTRALIAN SURVEYING & LAND INFORMATION GROUP 
Scrivener Building, Dunlop Court, Fern Hill Park, Bruce ACT 2617 
PO Box 2 Belconnen ACT 2616  Phone: +61 6 201 4201  Fax: +61 6 201 4366 
COMMONWEALTH OF AUSTRALIA 1995 
 
Zenith Distance 
 
The zenith distance is a vertical angle measured from directly overhead, down 
to the required point.  An ideal horizon has a zenith distance of 90 degrees. 
 
Vertical angle 
 
The Vertical angle is the angle measured in a vertical plane, from the horizon 
to the required point.  Directly overhead would have a vertical angle of 90
degrees.