The handbook is written in English, like the app.

Seestar Downloader — User Handbook

Version 1.3.1

Seestar Downloader copies the images from your ZWO Seestar — the stacked FITS files, the finished JPEG pictures and their thumbnails — onto your computer, over your network.

It works together with the official Seestar app: the Seestar app makes the connection to the telescope, and Seestar Downloader uses that same connection to fetch the files. So the one rule to remember is:

The Seestar app must be open and connected to your telescope while you download.

What you need

Your Seestar, switched on and connected in the Seestar app (on a phone, tablet or, on an Apple-Silicon Mac, the Seestar app itself). This works whether the telescope is on your own network or reached through ZWO's remote connection — as long as the Seestar app shows it as connected.
The device running the Seestar app and the computer running Seestar Downloader on the same local network (the same Wi-Fi / LAN).
Seestar Downloader, for macOS or Windows.

The two ways to connect

When Seestar Downloader starts, the top of the window has a “Connect to:” choice.

1. A device on the network (phone, tablet, or another Mac)

This is the usual case. One device on your network runs the Seestar app and is connected to the telescope; your computer downloads from it.

On the phone or tablet, open the Seestar app and connect to your telescope as you normally would.
Find that device’s IP address on your network:
- iPhone / iPad: Settings → Wi-Fi → tap the ⓘ next to your network → IP Address.
- Android: Settings → Wi-Fi → your network → Advanced / IP address. It looks like 192.168.0.177.
In Seestar Downloader choose “Device on the network…” and type that IP address.
Click Connect.

Your choice and the address are remembered, so next time you only click Connect.

2. The Seestar app on this Mac (macOS only)

On an Apple-Silicon Mac you can run the iPhone/iPad Seestar app directly on the Mac. If you do, and it is connected to your telescope, choose “Seestar app on this Mac” and click Refresh — no IP address needed.

On Windows there is no desktop Seestar app, so this option is switched off. On Windows you always use “Device on the network…” and point at your phone or tablet.

Downloading images

Connect (see above). The status line shows your telescope model and how many works were found, and the list fills with your objects, one line each. An object imaged several times says e.g. 8 stacks: click its arrow to unfold the images, newest first. Each line shows the date, the frames (e.g. 36 × 5 s, IRCUT, plus + 37 subs for a work that kept its individual frames) and the size; a folded object's size is that of all its images.
Optionally click Show thumbnails to see a small preview of each object.
Select what you want — click one line, or Ctrl/⌘-click and Shift-click for several. An object's own line stands for all its images; to get only some, unfold it and select those.
Choose what to download under “Download:”
- FITS (.fit) — the stacked data file, best for processing. These are large (tens of MB each).
- Full JPEG (.jpg) — the finished picture the Seestar produced.
- Thumbnail (.jpg) — a small preview image.
If anything selected belongs to a work that kept its individual frames (captured with “keep individual frames”), choose under “For works with subframes:”
- Stacked file only — just the one combined result.
- All files (stack + subframes) — the stacked file plus every raw subframe of the work, once per work however many of its images you select. The subframes are saved into a <name>_sub subfolder. This can be a lot of data — the Size column shows the total in brackets, e.g. 47.5 MB (all 633.0 MB).
Click Choose folder… to pick where the files go (your Downloads folder by default).
Click Download selected. Files already in the folder with the same size as on the telescope are left out; one of another size, such as an incomplete one, is downloaded again. To download everything again instead, change that in Settings (⚙).

While downloading you see:

the current file being downloaded, and its number in the queue (“file 2 of 5”),
an overall progress bar across all selected files,
a per-file progress bar with the size and percentage,
the speed and an estimated time remaining, and, if the connection broke off, the retry and whether it continued where the file stopped or had to start over (e.g. retry 1 of 3: continued at 1.7 MB). Afterwards the status line sums the retries up.

Stopping a download

Click Stop to cancel. The file currently in progress is stopped and its partial copy is removed; files already finished are kept.

Settings

Click ⚙ at the top right (or press ⌘, on a Mac). The settings are kept for the next start.

Retries per file (3 by default) — how often a file is tried again when the connection drops or stalls. A retry carries on where the file broke off.
Files already downloaded — Skip if the same size is already there (the default) or Download again and replace.
Speed limit — keeps downloads below a speed in KB/s, for example to leave room on a slow remote connection. No limit by default.
Allow changes on the Seestar (delete images) — off by default. While it is off the app only reads from the telescope, and Delete from Seestar… stays greyed out.

Deleting images from the Seestar

With changes allowed in Settings, select images and click Delete from Seestar…. The app lists what will be deleted and asks first. An unfolded image's line deletes just that image; an object's own line deletes the whole object: all its images and, if it kept them, its individual frames. If you pick every image of an object one by one, the object goes too, but its individual frames stay. An image's JPEG and preview go with it. Deleted images are gone from the telescope for good — download them first.

Good to know

The app changes nothing on your telescope unless you allow it in Settings; then it only deletes the images you choose and confirm. It does not send anything to the internet.
Downloads happen one file at a time. With several large FITS files this can take a while — the speed shown is the speed of the connection to your telescope, not of the app.
Keep the Seestar app connected. If you close it or it loses the telescope, downloads stop working until it is connected again. If that happens, reconnect in the Seestar app and click Refresh / Connect.
File names keep the Seestar’s own naming, e.g. Stacked_132_mosaic_NGC 3372_10.0s_LP_20261105-052445.fit, so they stay easy to match to your sessions and mosaic panels.

Troubleshooting

“Seestar not reachable.” - Is the Seestar app open and connected to the telescope right now? - Are both devices on the same network? - In network mode, is the IP address correct? (Re-check it on the phone/tablet — some networks hand out a new address after a while.)

The list is empty after connecting. - The telescope may simply have no saved works yet, or they are of a kind not listed. Capture something, then click Refresh.

A download failed or was skipped. - If the connection drops or stalls during a file, the app tries again by itself, up to three times, and carries on where the file broke off; the status line shows “retrying (1 of 3)…”. Only when that fails too is the file reported, with how far it got. - A file only appears under its name once it has arrived completely; a failed transfer leaves no partial copy behind. - Try again later — a slow or unstable connection to the telescope (for example over the remote network) is the usual cause. If one particular file always fails, it may still be processing on the telescope; give it a moment and refresh.

About, Support, Help

About — version and terms of use. Seestar Downloader is donationware for private use, and is not affiliated with ZWO.
Support — ways to donate. Every donation goes to the Smart Sky Survey project, which this app is a spin-off of. Donations are voluntary.
Help — opens this handbook.

Website and news: smm.smartskysurvey.com.

Not affiliated with ZWO. ZWO and Seestar are trademarks of their owner.