How to enter your own values manually?

[7yl4r]

I've recieved this question a few times:

I want to make a custom Pulsar Map and saw your Mapping Editor. Where did you get the values from the Pulsar Stars or how can i get these values (distance; z-coord; degrees; period)

Rather than continuing to address via email I am going to add resources and snippets from email conversations here until I can save up enough time/money to fix this properly.

One of the main reasons I have not implemented more customization yet is because it is fairly easy to do the calculations by hand, but first you need to specify how you want to calculate changes in the original 14 pulsars.

1. simple interpolation between the original measurements and the current data. This is quick and easy and results in a map which more closely resembles the original map. I have used the this interpolation spreadsheet to do this in the past: pulsar map interpolation method

2. Use the most current measurements and derivatives to calculate data for a given date. Although I think this is more accurate, the original data was actually pretty far off of reality so maps come out looking pretty different. For this use the integration spreadsheet: pulsar map itegration method

I will post more in comments below as I dig it out of my email archives.

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With thanks to the following for keeping the conversation going (in no particular order):

• Reilly Scull
• Jason Cihelka
• Tom Riecken
• Christopher Baan
• Dillon Thomison
• Nico Schrott
• Mike G

[7yl4r]

You may find a bit more info in this writeup.
The best source of pulsar data is the ATNF pulsar catalogue, but I don't believe that database will calculate values at a given time.
Position and rotational period at any time should be fairly straightforward to estimate given the proper motion of the object and the expected change in period over time.
For the latter, this is not necessarily a linear change, but that will likely give a decent approximation for recent dates.
Also keep in mind that actual position and rotation might differ significantly from our simple model, so we would ideally be using historical measurements here. The easiest way that I have found, however, is to trust wolfram alpha to do this for you.
The trouble is, no matter what date I put in, the rotational period seems to be the same... I'm not sure if this is because there is no significant change in that time, or wolfram alpha is simply neglecting the calculations...

all the necessary data is indeed in the ATNF pulsar database. For such a short time period the location change is surely negligible, but to backtrack the period you can use the given period (P0) along with the measurement date (PEpoch) and the time-derivative of period (P1). I did notice that there is also a proper-motion-corrected time-derivative P1_i, and that the calculations may be better done using frequency (F0), since higher-order time-derivatives are available for some pulsars (F1, F2, F3...). At least that is my understanding of it...

[7yl4r]

Spreadsheet and explaination provided by Reilly Scull 2015-02:

I've gotten a bit further along in my calculations. I used 3 sets of data and tried to do my best to make sense of it all. I used current ANTF data, Johnson Archive data, and lastly, measurements obtained from "The Astronomical Almanac 1990" which gave Period, Pdot, and epoch data. I tried to work out the periods to my birthday (4/24/90) and put all of this into a excel doc. Right now, if i did this math correctly, it looks like i can correctly calculate it to within a few days in most cases, and a few weeks in others. I'm attaching that excel doc to this email.

within the xlsx doc, there are 3 pages, the first congaing raw data, the second calculating errors between the data sets vs the calculations, and the third containing the calculations to by birthday.
I didn't have a chance to check out the calculations using F0 or the proper-motion-corrected time derivatives you mentioned. Interest to know if u figure that bit out. After i've checked my math a few more times.

• Pulsar Math.xlsx

[7yl4r]

Did you figure out any more clues on why the galactic coordinates (XX, YY, ZZ) don't match up trigonometrically with the galactic latitude and longitude values (G_l and G_b)?

I am working on this more detailed spreadsheet and that is driving me nuts. I have tried all possible combinations with the idea that maybe x,y,z do not align as I expect, but get nothing close to the right values in any orientation (see "trig exaustive search..." on the "calc-X" sheet).

Dillon Thomison: I could never figure out why they didn't match up. I always assumed with the distance, angle in the plane, and angle above/below the plane you could translate those into the coordinates. My only guess is that as the database is updated they don't measure/calculate all of the values in the table. So maybe the G_l and G_b were updated in 2010, but the coordinates haven't been updated since 1970 or something.

I just ended up using the galactic longitude and latitude to draw mine. I think it would be the thing that actually gets measured at updated regularly since the coordinates must be calculated by measuring the angles.

It is quite bizarre. I have opened a question on the astronomy stack exchange, although I don't know how active that community is. Your guess that some of the values are older is the best guess I have heard so far.

Mike G: The ATNF Pulsar Catalogue's galactic longitude and latitude are heliocentric, but the origin of their rectangular coordinates is near the center of our galaxy.

[Hengsto]

I would donate via Bitcoin

[7yl4r]

I would donate via Bitcoin

Thanks @DieHengst . It looks like my use of the coinbase API has broken on the app itself, but you can send to this address 37BEspzVYtK4D4RsbNJqGCb12S6EzQXkhD
Please contact via email ([email protected]) if you want to request work on something specifically.
Anything donated will go towards work on the open source parts of this... which is all of it now that I'm publishing those spreadsheets.