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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

3820 results found.

  1. EP261015a: AZT-20 Assy-Turgen optical observations
  2. GRB 261020A: Fermi GBM Observation
  3. GRB 261020A: MAXI GSC detection
  4. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  5. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  6. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  7. GRB 261011A: SAO RAS and AbAO optical observations
  8. GRB 261013A: Fermi GBM Final Real-time Localization
  9. MAXI GRB261012.23: Global MASTER-Net observations report
  10. GRB 261012A: MAXI GSC detection
  11. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  12. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  13. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  14. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  15. EP261006a: Optical follow-up observations with MATCH
  16. EP261007b: NOT optical observations, variable source outside the FXT region
  17. EP261006a: Early Optical Observations by WFST
  18. GRB 261007A: SVOM/COLIBRÍ (FM-GFT) optical observations
  19. SVOM GRB261007.23: Global MASTER-Net observations report
  20. EP261006a: Einstein Probe detection of an X-ray transient
  21. EP trigger 01709320985: SVOM/C-GFT optical upper limits
  22. GRB 260930B: Fermi GBM Final Real-time Localization
  23. EP260924a: Global MASTER-Net observations report
  24. GRB 260924A: Ondrejov D50 optical afterglow detection
  25. GRB 260924A: NOT optical counterpart confirmation
  26. Fermi GRB 260923A: Global MASTER-Net observations report
  27. EP Alert 260921.01: Global MASTER-Net observations report
  28. EP260920a: NOT optical upper limits
  29. EP260917a: Global MASTER-Net observations report
  30. EP260920a: COLIBRÍ optical upper limits
  31. EP Alert 260918.24: Global MASTER-Net observations report
  32. SVOM GRB260918.16: Global MASTER-Net observations report
  33. EP Alert 260917.32: Global MASTER-Net observations report
  34. GRB 260916A: MAXI/GSC detection
  35. MAXI GRB260916.37: Global MASTER-Net observations report
  36. EP Alert 260914.53: Global MASTER-Net observations report
  37. SVOM GRB260914.47: Global MASTER-Net observations report
  38. EP Alert 260909.53: Global MASTER-Net observations report
  39. Fermi GRB 260907B: Global MASTER-Net observations report
  40. Fermi GRB 260907A: Global MASTER-Net observations report
  41. EP Alert 260905.11: Global MASTER-Net observations report
  42. The EP-WXT trigger 01709302592 is likely a flaring star
  43. EP Alert 260903.62: Global MASTER-Net observations report
  44. NuSTAR Transient 260828: SOAR Optical Upper Limits
  45. MAXI GRB260827.40: Global MASTER-Net observations report
  46. EP Alert 260820.31: Global MASTER-Net observations report
  47. GRB 260809A: SVOM/ECLAIRs refined analysis
  48. IceCube Alert 260825A: Global MASTER-Net observations report
  49. SVOM trigger sb26081806 is not a GRB
  50. EP260806a: SAO RAS multicolor optical observations
  51. EP260806a: SVOM/ECLAIRs detection through targeted search
  52. Fermi GBM Sub-Threshold Detection of GRB 260809A
  53. GRB 260808B: J-band upper limit with WINTER
  54. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  55. GRB 260809A: SVOM detection of a faint burst
  56. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  57. Fermi GRB 260805A: Global MASTER-Net observations report
  58. Fermi GRB 260802B: Global MASTER-Net observations report
  59. GRB 260726A: SVOM/ECLAIRs refined analysis
  60. EP260727a: Einstein Probe detection of an X-ray transient
  61. Fermi GRB 260726A: Global MASTER-Net observations report
  62. EP260723a: Liverpool Telescope likely optical counterpart
  63. Fermi GRB 260718A: Global MASTER-Net observations report
  64. EP260703a: SVOM/ECLAIRs Upper Limit
  65. GRB 260714B: Fermi-LAT detection
  66. EP260713a: Einstein Probe detection of an X-ray transient
  67. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  68. IceCube Alert 260709A: Global MASTER-Net observations report
  69. GRB260708B: MAXI/GSC detection
  70. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  71. EP260703a: EP-WXT detection of a fast X-ray transient
  72. Fermi trigger No 804552016: Global MASTER-Net observations report
  73. EP260628a: EP-FXT follow-up observation
  74. EP260623a: Liverpool Telescope optical observations
  75. EP260623a: REM optical/NIR afterglow detection
  76. GRB 260616C: GECAM-B observation of a burst
  77. Konus-Wind detection of GRB 260616A
  78. GRB260616C: MAXI/GSC detection
  79. GRB 260614A: AstroSat CZTI detection
  80. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  81. GRB 260531B: Glowbug gamma-ray detection
  82. Fermi GRB 260601A: Global MASTER-Net observations report
  83. Fermi trigger No 801900520: Global MASTER-Net observations report
  84. GRB 260531B: Fermi GBM Final Real-time Localization
  85. GRB 260531A: MAXI/GSC detection
  86. GRB 260529A: Fermi GBM Final Real-time Localization
  87. EP260526a: SVOM/VT optical upper limits
  88. EP260527a: SVOM/VT optical observation
  89. Fermi trigger No 801580882: Global MASTER-Net observations report
  90. Fermi trigger No 801135305: Global MASTER-Net observations report
  91. GRB 260516D: GROWTH-India Telescope optical detection
  92. GRB 260515A: CrAO ZTSh BVRI optical observations
  93. SVOM GRB 260515A: Global MASTER-Net observations report
  94. GRB 260510C: Glowbug gamma-ray detection
  95. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  96. EP260514a: Global MASTER-Net observations report
  97. GRB 260511B: further SAO RAS optical observations
  98. GRB 260510C: Fermi GBM Observation
  99. GRB 260511A: NuSTAR detection of prompt emission
  100. GRB 260510C: AstroSat CZTI detection

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