ISS CubeSat Deploment (2021-03-14): TAUSAT-1, OPUSAT-II, GuaraniSat-1 (BIRDS-4), Maya-2 (BIRDS-4), Tsuru (BIRDS-4), RSP-01, WARP-01, STARS-EC

We have 8 “0 TBA - TO BE ASSIGNED” TLE sets from spacetrack for this deployment. We are going to wait assignment before identify them in DB, until then these are the current fits (with bold what we follow in DB and Network):

  • TAUSAT-1: OBJECT SC(47926)

    • It’s very clear as there isn’t any other object near it
  • OPUSAT-II: haven’t been received we follow OBJECT SA(47924)

    • An almost random choice
  • TSURU: one of OBJECT SB(47925), OBJECT SD(47927)

    • 99.99% that is OBJECT SD as in some of the observations doesn’t fit OBJECT SB well, but let’s have some more observations
  • MAYA-2: one of OBJECT SF(47929), OBJECT SG(47930), OBJECT SH(47931)

    • Too close to say for sure, given also that the last good observation was ~24h ago.
  • GUARANISAT-1: one of OBJECT SF(47929), OBJECT SG(47930), OBJECT SH(47931)

    • Too close to say for sure, given also that the last good observation was more than 48h ago.
  • RSP-01: one of OBJECT SB(47925), OBJECT SD(47927), OBJECT SE(47928)

    • Given that OBJECT SD and SE are fitting better to other satellites, 90% it is OBJECT SB, however we need more observations to say for sure.
  • WARP-01: haven’t been received we follow OBJECT SH(47931)

    • An almost random choice
  • STARS-EC: OBJECT SE(47928)

    • It’s very clear as in some observations there isn’t any other object near it
1 Like

After receiving OPUSAT-II, it seems to fit one of we have changed the TLE set to follow OBJECT SF(47929), OBJECT SG(47930), OBJECT SH(47931) but it still to close to say.

I’ve changed it to follow OBJECT SH(47931) for now in DB. Still TLE sets are TBA(TO BE ASSIGNED) so we need to wait for any identification.

EDIT: Note that the TLE are 2 days old so it may fit other objects too…


After further analysis OBJECT SB(47925) and OBJECT SD(47927) are also good candidates for OPUSAT-II.


Hi, we had confirmed, J-SSSOD24(OBJECT SH) is OPUSAT-Ⅱ. After one week of tracking, finally getting the first signal from OPUSAT-Ⅱ.

1 Like

@eon I think we need to wait as TLE are:

  1. still TBA and
  2. almost 3 days old.

However we changed our initial NORAD ID and follow OBJECT SH(47931) for OPUSAT-II for now.

1 Like

With new TLE sets from spacetrack we have the updates bellow:

  • TAUSAT-1: identified as OBJECT SC(47926)

  • OPUSAT-II: one of OBJECT SF(47929), OBJECT SG(47930), OBJECT SH(47931)

    • We have rejected two objects, OBJECT SB(47925) and OBJECT SD(47927), the rest are still to close, we need more observations.
  • TSURU: identified as OBJECT SD(47927)

  • MAYA-2: one of OBJECT SF(47929), OBJECT SG(47930), OBJECT SH(47931)

    • From previous data as we haven’t received it for a couple of days
  • GUARANISAT-1: one of OBJECT SF(47929), OBJECT SG(47930), OBJECT SH(47931)

    • From previous data as we haven’t received it for a couple of days
  • RSP-01: identified as OBJECT SB(47925)

    • Here are the results of ikhnos on observation 3816752. SD and SE Objects looks to be close but are 100% identified as other satellites and have a slight difference on this and other observations.
  • WARP-01: haven’t been received but given the current and previous fits it should be OBJECT SA(47924), need more observations and identify all the other objects of this launch to be 100% sure.

  • STARS-EC: identified as OBJECT SE(47928)

1 Like

I’ve changed the TLE we follow for OPUSAT-II as in the latest observation there was a slight curve, so for now it is going to follow OBJECT SF(47929). As Guaranisat-1 was following OBJECT SF(47929) I decided to change it to OBJECT SH(47931) that OPUSAT-II was following.

Still the objects are too close for any identification.

1 Like

@fredy you were right. OBJECT SH(47931) and OBJECT SG(47930) are great guesses for OPUSAT-2. But we found out that yesterday during MEL83deg pass, doppler shift correction was not 100% accurate by using OBJECT SH(47931). We have changed to use OBJECT SG(47930) as OPUSAT-2 for now.

1 Like

@eon Cool! I’ve changed it to OBJECT SG(47930), but still it is too close with the other objects to identify it. Hopefully the next days we will have a separation enough for identification. Could you inform us about the status of the satellite, if anything looks good? Also any hint why it didn’t started transmitting after the deployment but some days later?

@fredy OPUSAT-2 is doing great as in battery voltage, 0 abnormity counter after deployment from ISS, getting great signal even during low MEL degree pass.
That is one of the misterious. We assumed that is due to the antenna of satellite failed to deploy by using nichrome wire. As we have set it automatically execute the antenna deployment every 24hours if did not received any signal from ground station. After 8th attempts only successful deploy by it self, and finally got the first signal on 21th March (UTC11:27).


@fredy Hi, we are highly believed OBJECT SG(47930) is OPUSAT-2. We had tried both OBJECT SH and OBJECT SF 's TLE and found out both of it doppler shift correction were not accurate.

1 Like

My method is using ikhnos which is not as accurate as other methods like using strf tools. With my method SG seems to be the best fit, but the rest are still too close for letting me say that 100% is SG.

If your calculations and methods are more accurate than ikhnos ones, please provide the data that shows the fit, so we can identify it and change its NORAD ID in both DB and Network.


OPUSAT-II is now identified as OBJECT SG( 47930), here are the results of ikhnos on observation 3879619.

@eon given that OPUSAT-II signal is strong, do you know if it is expected to start transmit on other modes than CW?

Remaining satellites for identification are two of the Birds4, MAYA-2 and GUARANISAT-1, and WARP-01.

WARP-01 hasn’t been received until now, while the two of the Birds4 haven’t been received for more than 15 days( and

From the deployment times and the receptions we continue to follow OBJECT SA(47924) for WARP-01, OBJECT SF(47929) for MAYA-2 and OBJECT SH(47931) for GUARANISAT-1.

MAYA-2 was received in 3 observations of TSURU at around 2021-04-04 12:50 UTC and around 2021-04-04 13:21:48 UTC:

3894646 by 1667 - AAS Berga Carballada
3894332 by 753 - UY0LL
3894298 by 692 - VK4XSS-70

Here are the results of ikhnos for the 2 of the 3 observations which prove identification of MAYA-2 as OBJECT SF(47929) and bellow is the image showing the CW in the waveform of observation 3894332 that confirms the callsign of MAYA-2:

Unfortunately we didn’t have any other reception after these ones.

The only unidentified satellites from this launch is WARP-01 and GURANISAT-1. That latter has been received in the past, so we expect to receive it again, as happened with MAYA-1. WARP-01 hasn’t been received yet from SatNOGS Network, however there are reports in twitter, like the one bellow, that report reception of WARP-01:

After @PE0SAT said that he has seen something in strf which looks like WARP-01, I’ve checked and we have received multiple times WARP-01 the last hours.

With this we can identify WARP-01 as OBJECT SA(47924) and the remaining GUARANISAT-1 as OBJECT SH(47931).

Here are the results of ikhnos on observation 3890651 for WARP-01.

So bellow is the summary for this deployment:

1 Like

I am a student of Osaka Prefecture Univ. and a member of the OPUSAT-II (HIROGARI) operation team .

First of all, I’d like to say thank you for everyone here for identifying CubeSats including our OPUSAT-II.
Informations here were so helpful for us to identify and find our satellite.

Today, I’m sending this message to inform about message box service of our satellite.

Message box service is for amateur radio operators. Amateur radio operators can uplink messages to OPUSAT-II, and can downlink them by FM downlink. Therefore, Amateur radio operators ALL OVER THE WORLD can share massages through OPUSAT-II.
OPUSAT-II (HIROGARI) mission description

We will conduct test operation of the message box on the following schedule.
June 18, 9:47pm - June 19, 4:18am
June 19, 10:34pm-June 20, 3:28am

The informations needed to join this service (such as command format and generator, uplink/downlink mode and frequency, decode software) are available on the following link.

I remember that @fredy was wondering whether OPUSAT-II transmit on other modes than CW.
Answering this, OPUSAT-II transmits FM only when command uplinked, which means OPUSAT-II usually transmits FM only over Japan(because we uplink mission command from Japan).
But during conducting message box service, it transmits FM on other areas if amateur radio operators join the service and uplink message box commands. (Uplink command which is not from us is acceptable only when conducting message box service)

I would like lots of amateur radio operator all over the world to join.
If you have any question, please reply.


Thanks @forestwaterfall for the detailed message!

I’m going to schedule some observations with random downlink modes as it depends on what the uplink message will select. However if anyone is going to try a specific mode let us know here so we can schedule to receive that specific downlink mode.

EDIT: observations have been scheduled for both days.

Opusat-II was transmitting CW, but was received in FM mode. The strange thing is, that at 3:21 a local repeater was heard. DB0HHH transmitts on 145.750 MHz and is located 40 km away from my location.
I just checked the repeater transmission with my dx antenna (M2, 2M5WL), the signal is clean.

1 Like

STARS-EC is near its re-entry, so here is a TLE set generated by @cgbsat based on doppler:

1 47928U          22099.62500000  .00000000  00000-0  17282-2 0    00
2 47928  51.6294 287.7297 0007157 247.1227 189.5206 15.98329965    04

STARS-EC starts to deviate from its TLE. The TLE is 2 days old now, and I don’t know when to expect a new one. Anyway, I have fitted MA and MM to get a new one. I also tried B*, but that did not change. Propagated TLE:

1 47928U          22104.49996528  .00000000  00000-0  17877-2 0    06
2 47928  51.6253 261.8192 0012111 263.0413 267.6367 16.11487984000004
# 20220413.37-20220414.43, 117 measurements, 0.043 kHz rms

Edit: Fixed checksum