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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').

10046 results found.

  1. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  2. EP240708a: EP-WXT detection of a fast X-ray transient
  3. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  4. EP240703a and EP240703b: Swift/XRT upper limits
  5. EP240703a: BTA observations
  6. EP240703c: EP-WXT detection of an X-ray transient
  7. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  8. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  9. EP240703b: EP-WXT detection of a fast X-ray transient
  10. EP240702a: Swift/XRT upper limit
  11. EP240703a: EP-WXT detection of a fast X-ray transient
  12. EP240702a: EP-WXT detection of a fast X-ray transient
  13. GRB 240627A: CALET Gamma-Ray Burst Monitor detection
  14. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  15. GRB 240615A: SAI CMO J- band observations
  16. EP240625a: GRANDMA Optical Upper Limits
  17. EP240626a: EP-FXT detection of the X-ray emission
  18. EP240626a: EP-WXT detection of a fast X-ray transient
  19. GRB 240624B: CALET Gamma-Ray Burst Monitor detection
  20. EP240625a: NOT optical counterpart candidate
  21. EP240625a: EP-FXT detection of the X-ray emission
  22. GRB 240624B: GRBAlpha detection
  23. EP240625a: EP-WXT detection of a fast X-ray transient
  24. GRB240624A: Fermi GBM Observation
  25. Swift GRB 240624A: Global MASTER-Net observations report
  26. GRB 240624A: Swift detection of a burst
  27. GRB 240619A: GRBAlpha detection
  28. EP240618a: Swift/XRT upper limit
  29. EP240617a: tentative Swift/XRT detection of the afterglow
  30. GRB 240619A: CALET Gamma-Ray Burst Monitor detection
  31. Fermi GBM Sub-Threshold Detection of GRB 240619C
  32. EP240618a: Abastumani optical observationsEP240618a
  33. EP240618a: GRANDMA Optical Upper Limits
  34. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  35. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  36. EP240617a: EP-WXT detection of a fast X-ray transient
  37. EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
  38. GRB 240615A: GOTO optical upper limits
  39. GRB 240603A: VZLUSAT-2 detection
  40. GRB 240612A: GRBAlpha detection
  41. GRB 240529A : MITSuME Akeno optical afterglow detection
  42. The EP-WXT source triggered on June 1st is likely a flaring star
  43. GRB 240529A: AKO Optical Afterglow Follow-Up Observations
  44. GRB 240529A : Mondy optical observations
  45. GRB 240529A: Redshift from GTC/OSIRIS+
  46. LXT 240528A: LEIA detection of a fast X-ray transient
  47. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  48. GRB 240523A: Swift detection of a burst
  49. Fermi GBM Sub-Threshold Detection of GRB 240516B
  50. GRB 240514B: VZLUSAT-2 detection
  51. GRB 240504A: VZLUSAT-2 detection
  52. GRB 240502A: VZLUSAT-2 detection
  53. GRB 240519A: GRBAlpha detection
  54. GRB 240516A: Swift/UVOT Upper Limits
  55. EP240518a: possibly identified with a flare star by EP-FXT
  56. EP240518a: EP-WXT detection of a new X-ray transient
  57. GRB 240514E: A possible candidate BD-21 1074
  58. GRB 240511A: Observations from GTC/OSIRIS+
  59. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  60. GRB 240514E: MAXI/GSC detection of a probable afterglow
  61. GRB 240514B: GRBAlpha detection
  62. GRB 240513A: Fermi-LAT detection
  63. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  64. GRB 240511A : MITSuME Akeno optical upper limits
  65. GRB 240511A: Swift detection of a burst
  66. EP240506a: CrAO ZTSH optical upper limit
  67. EP240506a: EP-WXT detection of a new fast X-ray transient
  68. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  69. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  70. LXT 240402A / GRB 240402B: VLT X-shooter redshift of host
  71. GRB 240502C: GOTO possible optical counterpart candidates
  72. GRB 240501B: GRBAlpha detection
  73. GRB 240430A: GRBAlpha detection
  74. GRB 240426A: VZLUSAT-2 detection
  75. GRB 240425A: VZLUSAT-2 detection
  76. GRB 240408B: VZLUSAT-2 detection
  77. GRB 240407A: VZLUSAT-2 detection
  78. GRB 240425A: GRBAlpha detection
  79. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  80. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  81. EP240426b: EP-WXT detection of a new fast X-ray transient
  82. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  83. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  84. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  85. LVK S240422ed: Further Swift-XRT followup of three sources
  86. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  87. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search update and AT2024hfx, AT2024hgl observations
  88. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  89. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  90. LIGO/Virgo/KAGRA S240422ed: Vetting of DECam Candidates Using Real-Time Resources and SAGUARO Infrastructure
  91. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  92. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  93. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  94. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  95. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  96. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  97. GRB 240421B: GRBAlpha detection
  98. LIGO/Virgo/KAGRA S240422ed: SAGUARO upper limits from CSS
  99. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  100. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search

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