X-37B OTV 8 and Limasat (the USSF-36 payloads) imaged

 

This morning (early 24 August 2025) weather finally cooperated and I managed to observe both of the USSF-36 payloads, two days after launch: the X-37B Spaceplane OTV 8 (2025-183A) and  LIMASAT (2025-183B). Limasat was about half a minute in front of OTV 8.

Above is footage from this pass, showing both objects. The footage was obtained from my home in Leiden, the Netherlands, using a WATEC 902H2 Supreme camera with a Samyang 1.4/85 mm lens filming at 25 frames/second. This was an early twilight pass low in the south-southwest (27 degrees maximum elevation).

Below are framestacks from parts of the footage (both framestacks are 51-frame stacks):

Limasat (stack of 51 frames)

 

X-37B OTV 8 (stack of 51 frames)

 

Current observations show OTV 8 in a 331 x 342 km, 49.5 degree inclined orbit. Limasat is in a 330 x 341 km, 49.5 degree inclined orbit. Limasat was probably carried piggyback on the X-37B Service Module before being released.

X-37B Spaceplane mission OTV 8 located on orbit

OTV 8 imaged by Kevin Fetter 5 hours after launch. Image (c) Kevin Fetter, used with permission

OTV 8, the 8th mission of the US Space Force's X-37B Spaceplane, launched on 22 August 2025 at 03:50 UTC. It has been catalogued as 2025-183A (cat. nr. 65271) under the name of  'USA 555', along with a second payload, called LIMASAT (2025-183B, 65272). The latter has probably been dispensed from the OTV 8 service module.

Five hours after launch, Kevin Fetter managed to observe OTV 8. Above is one of his images, showing OTV 8 as a short bright trail in a partly cloudy sky. 

A preliminary orbit fit suggests that OTV 8 is in a 327 x 334 km, 49.5 degree inclined orbit [update 25 Aug 2025: the latest improved orbit update shows it in a 331 x 342 km, 49.5 degree inclined orbit]: a slightly (~20 km) lower orbital altitude than my initial pre-launch guess but otherwise a quite comparable orbit.

Click image to enlarge

 

An overview of the OTV missions so far: 

MISSION  ORBITER  LAUNCH   INCL   ORBIT   DURATION
--------------------------------------------------
OTV 1    I        2010     40.0   LEO     224 days
OTV 2    II       2011     42.8   LEO     468 days
OTV 3    I        2012     43.5   LEO     674 days
OTV 4    II       2015     38.0   LEO     717 days
OTV 5    II       2017     54.5   LEO     780 days
OTV 6    I        2020     45.0   LEO     909 days
OTV 7    II       2023     59.1   HEO     435 days
OTV 8    I        2025     49.5   LEO         tbd
--------------------------------------------------

Bad weather in the Netherlands has so far precluded me from trying to observe the latest launch.
 

EDIT (24 August 2025): 

I imaged both the USSF-36 payloads (OTV 8 and Limasat) in the early morning of 24 August, see this follow-up blogpost with footage.