16:34 on December 29th, over Paraguay pic.twitter.com/cDJTvovcQx— DSCOVR:EPIC (@dscovr_epic) December 31, 2015
If you’re interested, the Python source code is available on Github.
Which time zone are the image timestamps in?
The timestamps in the tweets are in UTC. Because of DSCOVR’s position in orbit around the Earth-Sun L1 Lagrange point – directly between the Earth and the Sun – the local time on Earth directly under DSCOVR is always around midday.
When are images posted?
EPIC currently takes between 10 and 13 pictures of Earth per day (although these pictures are each composed of 10 separete monochrome images in different wavelengths). Occasionally there are fewer pictures available per day, and sometimes there are none at all – the reasons for this variation aren’t clear.
Processed images from EPIC are published on NASA’s EPIC site, usually once per day for the previous day’s images, but delays in this process are common at the moment.
@dscovr_epic has a queue which spaces its tweets out over the course of the day. If everything is running normally on NASA’s side, the images are tweeted on average around 36 hours after they’re captured.
What processing is done on the images?
EPIC takes 10 separate exposures on different channels at a resolution of 2048x2048. Unfortunately, these images are then downscaled on the spacecraft to a resolution of 1024x1024 due to limited downlink bandwidth.
NASA then runs some unspecified processing on these images to combine them into a 2048x2048 full-colour PNG file which the bot downloads from their website.
@dscovr_epic performs some unscientific colour and contrast adjustment, downscaling, and sharpening to produce something which looks aesthetically pleasing on Twitter. The exact incantations used for this are here.
(Credit to Charlie Lloyd’s excellent post on the Mapbox blog for image processing tips.)
Why am I blocked by @dscovr_epic on Twitter?
I like reading @dscovr_epic’s Twitter mentions, and I will usually reply from my personal account to reasonable questions about the Earth, Earth observation, and EPIC.
I do not like reading interminable Twitter threads by people trying (and inevitably failing) to convince flat-earthers that they’re wrong.
If you’re blocked, it’s probably either because you:
- Believe the Earth is flat, in which case why are you replying to this bot which is clearly part of the conspiracy? I have not blocked you because I have something to hide; I’ve blocked you because I don’t think I can change your mind.
- Are trying to convince people that the Earth isn’t flat. Seriously, cut it out, it’s not worth it. You’re not going to change conspiracy theorists’ minds, especially not on Twitter. Get a more rewarding hobby.