With several days of lovely weather over the UK I've been paying attention to 94074B. On 12th April I could notice the tumbling (just - the sky was quite hazy and light pollution drove seeing down to about mag +3). It was something around +1.5 to +2.5, probably not even that big (!) a swing. 31 flashes in 40.33 seconds, ie a flash period of 1.30 seconds. Then on 13th April I spotted it again, under slightly better conditions. Similar light curve, counted 40 flashes in 51 seconds (it was at this point I realised that the button for the light on the stopwatch and the counter reset button are one and the same - great design! I glimpsed 51 before it was reset.) Thus 51/40 gives 1.28 and in the other extremem 51.99/40 gives 1.30 .
Hence 1.3 sec flash period seems about right.
This last evening (22nd April) I decided to try and see if I could spot the ERS-2 rocket and ERS-2 itself. Based on the element given below I went out and watched the eastern skies. At around 21:38 UTC I noticed a mag +3 object climbing in the ESE. Closely following it was a companion of similar brightness. They climbed up towards the zenith closely following the predicted path of ERS-2 but about 1 minute (in time) ahead of the expected position. At 21:40:01 UTC the leading object (appeared to have a very slight red tinge) passed between Alcor and Mizar (80 U Ma and 79 U Ma) 1/3 of the distance from Alcor to Mizar. About 6 seconds behind at this time the (white) following object passed on the opposite side of Alcor to Mizar, 6 times the Mizar-Alcor separation in distance from Alcor. At this point they were around mag. +2. I followed them as they faded and were lost in haze to the north.
The two were just under 2 degrees apart and given the separation in time and local elevation could have been associated with ERS-2 at an altitude of about 780 km. I looked for a 'third' object in case they were NOSS but couldn't see one (the most recent NOSS elements I have don't fit these observations).
Consequently I searched for them on the next pass low in the west and found two objects at about 15 degrees elevation, both around mag. +5.5, in the vicinity of Beta Cancri (at 23:19:15 UTC), where I expected to find ERS-2, again 1 minute ahead of expectation. Cloud and light pollution prevented me from following them for more than around 30 seconds but I could see that the separation of the two objects was now around 13 seconds in time.
I assume one object was ERS-2, but was the other the Ariane upper stage? During neither pass could I see any indication of flashing from either object. I don't know what the separation sequence and timeline is for the upper stage and any other payloads (were any craft being piggybacked on this mission as with ERS-1?). I assume that only the rocket stage and ERS-2 could be such bright (and equally so) objects (ie anything else would be significantly smaller). Does anyone have any details for the rocket or other payloads?