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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').

10043 results found.

  1. EP240703a and EP240703b: Swift/XRT upper limits
  2. EP240703a: BTA observations
  3. EP240703c: EP-WXT detection of an X-ray transient
  4. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  5. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  6. EP240703b: EP-WXT detection of a fast X-ray transient
  7. EP240702a: Swift/XRT upper limit
  8. EP240703a: EP-WXT detection of a fast X-ray transient
  9. EP240702a: EP-WXT detection of a fast X-ray transient
  10. GRB 240627A: CALET Gamma-Ray Burst Monitor detection
  11. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  12. GRB 240615A: SAI CMO J- band observations
  13. EP240625a: GRANDMA Optical Upper Limits
  14. EP240626a: EP-FXT detection of the X-ray emission
  15. EP240626a: EP-WXT detection of a fast X-ray transient
  16. GRB 240624B: CALET Gamma-Ray Burst Monitor detection
  17. EP240625a: NOT optical counterpart candidate
  18. EP240625a: EP-FXT detection of the X-ray emission
  19. GRB 240624B: GRBAlpha detection
  20. EP240625a: EP-WXT detection of a fast X-ray transient
  21. GRB240624A: Fermi GBM Observation
  22. Swift GRB 240624A: Global MASTER-Net observations report
  23. GRB 240624A: Swift detection of a burst
  24. GRB 240619A: GRBAlpha detection
  25. EP240618a: Swift/XRT upper limit
  26. EP240617a: tentative Swift/XRT detection of the afterglow
  27. GRB 240619A: CALET Gamma-Ray Burst Monitor detection
  28. Fermi GBM Sub-Threshold Detection of GRB 240619C
  29. EP240618a: Abastumani optical observationsEP240618a
  30. EP240618a: GRANDMA Optical Upper Limits
  31. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  32. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  33. EP240617a: EP-WXT detection of a fast X-ray transient
  34. EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
  35. GRB 240615A: GOTO optical upper limits
  36. GRB 240603A: VZLUSAT-2 detection
  37. GRB 240612A: GRBAlpha detection
  38. GRB 240529A : MITSuME Akeno optical afterglow detection
  39. The EP-WXT source triggered on June 1st is likely a flaring star
  40. GRB 240529A: AKO Optical Afterglow Follow-Up Observations
  41. GRB 240529A : Mondy optical observations
  42. GRB 240529A: Redshift from GTC/OSIRIS+
  43. LXT 240528A: LEIA detection of a fast X-ray transient
  44. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  45. GRB 240523A: Swift detection of a burst
  46. Fermi GBM Sub-Threshold Detection of GRB 240516B
  47. GRB 240514B: VZLUSAT-2 detection
  48. GRB 240504A: VZLUSAT-2 detection
  49. GRB 240502A: VZLUSAT-2 detection
  50. GRB 240519A: GRBAlpha detection
  51. GRB 240516A: Swift/UVOT Upper Limits
  52. EP240518a: possibly identified with a flare star by EP-FXT
  53. EP240518a: EP-WXT detection of a new X-ray transient
  54. GRB 240514E: A possible candidate BD-21 1074
  55. GRB 240511A: Observations from GTC/OSIRIS+
  56. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  57. GRB 240514E: MAXI/GSC detection of a probable afterglow
  58. GRB 240514B: GRBAlpha detection
  59. GRB 240513A: Fermi-LAT detection
  60. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  61. GRB 240511A : MITSuME Akeno optical upper limits
  62. GRB 240511A: Swift detection of a burst
  63. EP240506a: CrAO ZTSH optical upper limit
  64. EP240506a: EP-WXT detection of a new fast X-ray transient
  65. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  66. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  67. LXT 240402A / GRB 240402B: VLT X-shooter redshift of host
  68. GRB 240502C: GOTO possible optical counterpart candidates
  69. GRB 240501B: GRBAlpha detection
  70. GRB 240430A: GRBAlpha detection
  71. GRB 240426A: VZLUSAT-2 detection
  72. GRB 240425A: VZLUSAT-2 detection
  73. GRB 240408B: VZLUSAT-2 detection
  74. GRB 240407A: VZLUSAT-2 detection
  75. GRB 240425A: GRBAlpha detection
  76. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  77. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  78. EP240426b: EP-WXT detection of a new fast X-ray transient
  79. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  80. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  81. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  82. LVK S240422ed: Further Swift-XRT followup of three sources
  83. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  84. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  85. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  86. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  87. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  88. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  89. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  90. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  91. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  92. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  93. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  94. GRB 240421B: GRBAlpha detection
  95. LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
  96. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  97. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  98. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  99. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  100. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations

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