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updates to src/imaging/calibration.md; temp url fix (#60)
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* added linebreaks before images in src/imaging/calibration.md, cleaned up some md and punctuation

* More detailed info on dark flats 

https://www.cloudynights.com/topic/697829-what-is-a-dark-flat-and-how-do-i-take-it/

* updated broken discord links... for now; these will expire again; see https://discord.com/channels/600359252753776670/1158883919807135815/1265945932508172359

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Co-authored-by: kadix <[email protected]>
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kadixfox and kadix authored Jul 26, 2024
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13 changes: 6 additions & 7 deletions src/imaging/calibration.md
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Expand Up @@ -6,10 +6,10 @@ Here's a quick primer on how to take calibration frames. These are pretty easy t
## Flats
Flats correct for dust on your optical train and vignetting from the telescope and your optics.
Take about 25-30 of these. Ask around! Everyone does them differently...
There are a few good methods to take them. An easy method for beginners is to move the telescope so it's pointing at the zenith and then use a rubber band to secure a white t-shirt to the front of the telescope. Then, put a white image on your phone screen at max brightness and place it on the telescope. Keep the settings the same as when you took the light frames, but lower the exposure until the histogram fits in the middle.
There are a few good methods to take them. An easy method for beginners is to move the telescope so it's pointing at the zenith and then use a rubber band to secure a white t-shirt to the front of the telescope. Then, put a white image on your phone screen at max brightness and place it on the telescope. Keep the settings the same as when you took the light frames, but lower the exposure until the histogram fits in the middle.\
![image](https://github.com/observational-dev/oawiki/assets/31824839/8a6c365e-8ffc-4d86-b397-a845ba2f7c75)

If you took them correctly, your flat frame will look something like this:
If you took them correctly, your flat frame will look something like this:\
![image](https://github.com/observational-dev/oawiki/assets/31824839/b93ab15a-624b-4f90-9794-26e892b62d99)

## Biases
Expand All @@ -20,11 +20,10 @@ Take exposures at the fastest speed your shutter will go. For a DSLR that might
## Darks
These calibration frames correct for amp glow and hot/cold pixels. Dark frames are pure noise.
Take about 30-50 darks. These might take you a while if your exposure time is longer.
Shoot these before or after your session- make sure your camera has the same settings/ambient temp is the same
Shoot these before or after your session- make sure your camera has the same settings/ambient temp is the same.

## Extra frames:
Dark flats
These are nice if you have filters and it's fast to take these. It's not really useful for DSLRs but it's nice for astrocams. Same exposure length as the flats. measure dark current in the flat frame

![image](https://github.com/observational-dev/oawiki/assets/31824839/e21394c6-28f3-4730-ba13-dd7f69d6368f)
### Dark flats:
These are dark frames for your flat frames using the same settings as the flats, nice if you have filters and it's fast to take these. It's not really useful for DSLRs but it's nice for astrocams. Same exposure length as the flats.\
![image](https://github.com/observational-dev/oawiki/assets/31824839/e21394c6-28f3-4730-ba13-dd7f69d6368f)\
Here's Noah!
4 changes: 2 additions & 2 deletions src/other/examplepage.md
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Expand Up @@ -24,7 +24,7 @@ A quick markdown [cheatsheet](https://commonmark.org/help/) is available, as wel
...And a cat image for you:[^catref]
[^catref]: Locke, 2023, used with permission

![a cat yawns, Locke 2023, used with permission](https://cdn.discordapp.com/attachments/514888013533151253/1157127122570190998/PXL_20230929_012816945.PORTRAIT.jpg)
![a cat yawns, Locke 2023, used with permission](https://cdn.discordapp.com/attachments/514888013533151253/1157127122570190998/PXL_20230929_012816945.PORTRAIT.jpg?ex=66a2fc1c&is=66a1aa9c&hm=141f82a0e26e4591dd3f55e826a33cb7bb14ced4bcb63aa176c4f8c36d65b0b8&)

> This is a blockquote. It's useful for separating out a specific chunk of text from the rest. Glass does not flow at room temperature as a high-viscosity liquid. Although glass shares some molecular properties with liquids, it is a solid at room temperature and only begins to flow at hundreds of degrees above room temperature. Old glass which is thicker at the bottom than at the top comes from the production process, not from slow flow; no such distortion is observed in other glass objects of similar or even greater age
>
Expand Down Expand Up @@ -68,7 +68,7 @@ Absolutely! It's documented [here](https://sphinx-design.readthedocs.io/en/lates
% This line is a comment and will not show up on the wiki page.
% It's like a secret for wiki editors only.

```{figure} https://cdn.discordapp.com/attachments/514888013533151253/1125231069092913153/PXL_20230703_010350269.PORTRAIT.ORIGINAL.jpg
```{figure} https://cdn.discordapp.com/attachments/514888013533151253/1125231069092913153/PXL_20230703_010350269.PORTRAIT.ORIGINAL.jpg?ex=66a2f698&is=66a1a518&hm=a7bd6de2559e93c75336924b315173b1b77c7d9434d30d261d8f1dcf70ba1900&
:align: right
:figwidth: 30%
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