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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').

10041 results found.

  1. EP240703c: EP-WXT detection of an X-ray transient
  2. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  3. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  4. EP240703b: EP-WXT detection of a fast X-ray transient
  5. EP240702a: Swift/XRT upper limit
  6. EP240703a: EP-WXT detection of a fast X-ray transient
  7. EP240702a: EP-WXT detection of a fast X-ray transient
  8. GRB 240627A: CALET Gamma-Ray Burst Monitor detection
  9. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  10. GRB 240615A: SAI CMO J- band observations
  11. EP240625a: GRANDMA Optical Upper Limits
  12. EP240626a: EP-FXT detection of the X-ray emission
  13. EP240626a: EP-WXT detection of a fast X-ray transient
  14. GRB 240624B: CALET Gamma-Ray Burst Monitor detection
  15. EP240625a: NOT optical counterpart candidate
  16. EP240625a: EP-FXT detection of the X-ray emission
  17. GRB 240624B: GRBAlpha detection
  18. EP240625a: EP-WXT detection of a fast X-ray transient
  19. GRB240624A: Fermi GBM Observation
  20. Swift GRB 240624A: Global MASTER-Net observations report
  21. GRB 240624A: Swift detection of a burst
  22. GRB 240619A: GRBAlpha detection
  23. EP240618a: Swift/XRT upper limit
  24. EP240617a: tentative Swift/XRT detection of the afterglow
  25. GRB 240619A: CALET Gamma-Ray Burst Monitor detection
  26. Fermi GBM Sub-Threshold Detection of GRB 240619C
  27. EP240618a: Abastumani optical observationsEP240618a
  28. EP240618a: GRANDMA Optical Upper Limits
  29. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  30. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  31. EP240617a: EP-WXT detection of a fast X-ray transient
  32. EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
  33. GRB 240615A: GOTO optical upper limits
  34. GRB 240603A: VZLUSAT-2 detection
  35. GRB 240612A: GRBAlpha detection
  36. GRB 240529A : MITSuME Akeno optical afterglow detection
  37. The EP-WXT source triggered on June 1st is likely a flaring star
  38. GRB 240529A: AKO Optical Afterglow Follow-Up Observations
  39. GRB 240529A : Mondy optical observations
  40. GRB 240529A: Redshift from GTC/OSIRIS+
  41. LXT 240528A: LEIA detection of a fast X-ray transient
  42. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  43. GRB 240523A: Swift detection of a burst
  44. Fermi GBM Sub-Threshold Detection of GRB 240516B
  45. GRB 240514B: VZLUSAT-2 detection
  46. GRB 240504A: VZLUSAT-2 detection
  47. GRB 240502A: VZLUSAT-2 detection
  48. GRB 240519A: GRBAlpha detection
  49. GRB 240516A: Swift/UVOT Upper Limits
  50. EP240518a: possibly identified with a flare star by EP-FXT
  51. EP240518a: EP-WXT detection of a new X-ray transient
  52. GRB 240514E: A possible candidate BD-21 1074
  53. GRB 240511A: Observations from GTC/OSIRIS+
  54. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  55. GRB 240514E: MAXI/GSC detection of a probable afterglow
  56. GRB 240514B: GRBAlpha detection
  57. GRB 240513A: Fermi-LAT detection
  58. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  59. GRB 240511A : MITSuME Akeno optical upper limits
  60. GRB 240511A: Swift detection of a burst
  61. EP240506a: CrAO ZTSH optical upper limit
  62. EP240506a: EP-WXT detection of a new fast X-ray transient
  63. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  64. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  65. LXT 240402A / GRB 240402B: VLT X-shooter redshift of host
  66. GRB 240502C: GOTO possible optical counterpart candidates
  67. GRB 240501B: GRBAlpha detection
  68. GRB 240430A: GRBAlpha detection
  69. GRB 240426A: VZLUSAT-2 detection
  70. GRB 240425A: VZLUSAT-2 detection
  71. GRB 240408B: VZLUSAT-2 detection
  72. GRB 240407A: VZLUSAT-2 detection
  73. GRB 240425A: GRBAlpha detection
  74. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  75. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  76. EP240426b: EP-WXT detection of a new fast X-ray transient
  77. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  78. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  79. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  80. LVK S240422ed: Further Swift-XRT followup of three sources
  81. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  82. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  83. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  84. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  85. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  86. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  87. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  88. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  89. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  90. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  91. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  92. GRB 240421B: GRBAlpha detection
  93. LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
  94. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  95. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  96. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  97. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  98. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  99. GRB 240414A: radio detection with the VLA
  100. GRB 240419B : MITSuME Akeno optical upper limits

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