DWARF 3 FITS Files: How to Copy Them and Stack Them on a Computer

The DWARF 3 stacks on the telescope and hands you a finished picture on your phone. It also keeps every raw frame it took, as a 16-bit linear FITS file, and those frames hold more than the picture on the phone: they can be graded one by one, the poor ones left out, satellite trails rejected across the whole set, and several nights added together.

This guide covers where the frames are, how to get them onto a computer and what to do with them.

How to copy the files to a computer

Connect the DWARF 3 to the computer with a USB cable (USB-A to USB-C or USB-C to USB-C, and it has to be a data cable, not a charge-only one). It appears as a drive called DWARF 3 on Windows and macOS, and you copy files from it like any other drive.

Two things from DwarfLab’s own help page are worth knowing:

• New files do not appear until you reconnect. Frames captured while the cable is in only show after you unplug and plug the telescope back in.
• It cannot write to an external drive. Everything stays on the telescope’s own storage until you copy it off.

DwarfLab also describes a wireless way to browse new files, but for a session of a few hundred frames the cable is much faster.

Where the frames are

Everything for the night sky is in the Astronomy folder:

Folder	What is in it
DWARF_RAW	One folder per session, holding that session’s raw frames and the telescope’s stacked results
CALI_FRAME	Darks, flats and bias frames: the factory set and the stacked darks from your own sessions, kept apart for the telephoto (cam_0) and wide-angle (cam_1) cameras
DWARF_DARK	Your own single dark frames
Restacked	Pictures made with the app’s Mega Stack
Solving_Failed	JPEGs from an attempt where the telescope could not work out where it was pointing

A session folder is named after the target, the exposure, the gain and the time, for example DWARF_RAW_M 42_EXP_15_GAIN_60_.... Every frame in one folder has the same exposure and gain. Beside the frames the telescope writes its stacked results (a 16-bit linear FITS, a stretched 16-bit PNG and an 8-bit JPEG), thumbnails, and a small shotsInfo.json that records the target, exposure, gain, filter, sensor temperature and how many frames it stacked.

Which folder to open

Open the session folder itself, the one that starts with DWARF_RAW_. In Akastroid, choose Choose folder on the Deep sky card and select it.

You do not need to tidy the folder first. Akastroid recognises the DWARF 3’s own stacked files and the thumbnails as pictures made from the frames, not frames, and leaves them out; the report says how many it set aside. It then grades the raw frames, leaves out the poor ones, stacks the rest, removes the light pollution gradient, balances the colour and finishes the picture without any settings.

Common questions

How do I view a DWARF 3 .fits file on a PC or Mac?

A FITS frame holds the raw numbers from the sensor, so most photo viewers show it black or refuse it: the data is linear and has not been stretched for a screen. Open it in software that reads FITS. In Akastroid, use Choose files for one stacked FITS, or Choose folder for a whole DWARF_RAW_ session.

Can I combine several nights of the same target?

Yes, and it is the biggest improvement you can make: two nights is twice the signal. Copy the raw frames of every night into one folder and open that folder. Restack from the frames rather than combining the telescope’s stacked files: a stack of stacks can only average finished pictures, so a hazy night weighs as much as a clear one, while starting from the frames lets each one be graded on its own.

What about the dual-band filter?

Frames taken through the DWARF 3’s dual-band filter hold mostly the red light of hydrogen and the green-blue light of oxygen. Keep them in a folder of their own, apart from frames taken with the astronomy filter, so each set is stacked and coloured for what it holds.

Do I need my own darks?

The DWARF 3 keeps darks in CALI_FRAME and applies them on the telescope. For a first try, open the raw session folder as it is. If you see hot pixels or a warm glow in a corner, take a set of darks at the same exposure, gain and temperature and add them to the session.

How do I get a TIFF for Lightroom or Photoshop?

Stack the frames, then export a 16-bit TIFF. Lightroom and Photoshop open it directly and keep every tone for further editing.

Can I process a DWARF 3 mosaic?

Yes. A folder of mosaic panels opened on the Deep sky card is sorted into its panels by the stars themselves; each panel is stacked and the panels are joined into one picture.

The free copy gives five processing runs and two exports, enough to try it on your own DWARF 3 session. Download Akastroid. The same approach for the ZWO Seestar is in the Seestar FITS guide.