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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').
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"

32494 results found.

  1. EP240913a: ESO-NTT optical observations
  2. GRB 240914A: ESO-NTT optical observations
  3. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  4. GRB 240905E: further NOT optical observations
  5. EP240913a: A GRB Event
  6. GRB 240911A: LCO optical observations
  7. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  8. Fermi Gamma-ray Burst Monitor trigger 747837485/240912526 is not a GRB
  9. GRB 240912A: Swift/UVOT Detection
  10. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  11. GRB 240912A: SVOM/GRM observation
  12. Fermi GRB 240913A: Global MASTER-Net observations report
  13. GRB 240912A: J-band observations with WINTER
  14. GRB 240912A: Fermi GBM Observation
  15. Swift GRB 240912A: Global MASTER-Net observations report
  16. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  17. GRB 240911A: Tiled Swift observations
  18. GRB 240912A : INTEGRAL SPI ACS LIGHT CURVE
  19. GRB 240912A: NOT optical spectroscopy
  20. GRB 240912A: Redshift from OSIRIS+/GTC
  21. Fast X-ray Transient EP240801a: GMRT radio observations
  22. GRB 240910A: Redshift from OSIRIS+/GTC
  23. GRB 240910A: Fermi GBM Observation
  24. GRB 240910A: NOT optical observations
  25. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  26. GRB 240910A: JinShan optical observations
  27. GRB 240910A: GOTO candidate optical counterpart
  28. EP240908a: Optical afterglow confirmation
  29. GRB 240710A: SVOM/GRM observation
  30. GRB 240910A: Swift ToO observations
  31. IPN triangulation of GRB 240905B (short)
  32. GRB 240825A: 7DT Optical Upper Limit
  33. GRB 240905E: SVOM/VT optical observations
  34. GRB 240905E: SVOM/VT optical observations (duplicate submission of GCN 37453)
  35. GRB 240910A: GRBAlpha detection
  36. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  37. LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
  38. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  39. GRB 240910A: SVOM/GRM observation
  40. EP240908a: Mondy and AbAO follow-up observations
  41. EP240908a: Updates on the WXT detection result around the trigger time
  42. Fermi GRB 240910A: Global MASTER-Net observations report
  43. EP240908a: optical afterglow candidate
  44. EP EP240908a: Global MASTER-Net observations report
  45. GRB 240905B: Fermi GBM Observation
  46. EP240908a: TRT optical upper limit
  47. GRB 240905B: GOTO optical upper limits
  48. Fermi GRB 240908A: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S240908dg: Updated Sky localization
  50. LIGO/Virgo/KAGRA S240908bs: Updated Sky localization
  51. LIGO/Virgo/KAGRA S240908dg: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S240908bs: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S240907cg: Updated Sky localization
  54. GRB 240801A: SVOM/GRM observation
  55. LIGO/Virgo/KAGRA S240907cg: Identification of a GW compact binary merger candidate
  56. GRB 240905E: GIT optical upper limit
  57. GRB 240905E: Gaoyazi/GOT optical upper limits
  58. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  59. GRB 240905B: Fermi-LAT detection
  60. GRB 240905B: Swift ToO observations
  61. GRB 240905E: J-band observations with WINTER
  62. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  63. GRB 240905E: AKO Optical Upper Limit
  64. GRB 240905E: SVOM/C-GFT optical upper limit
  65. GRB 240905E: OHP/MISTRAL T193 optical upper limit
  66. Fermi GRB 240905D: Global MASTER-Net observations report
  67. Fermi GRB 240905A: Global MASTER-Net observations report
  68. GRB 240905E: NOT optical upper limits
  69. GRB 240905E: REM optical/NIR upper limits
  70. GRB 240905E: SVOM/GRM observation
  71. GRB 240905E: LCOGT Optical Upper Limit
  72. GRB 240905E: Swift/UVOT Upper Limits
  73. GRB 240905E: SAO RAS optical upper limit
  74. GRB 240825A: Montarrenti Observatory optical follow-up observations
  75. GRB 240905E: Nanshan/HMT optical upper limit
  76. Swift GRB 240905E: Global MASTER-Net observations report
  77. GRB 240819A: Optical upper limits from TESS
  78. GRB 240905D: AstroSat CZTI detection
  79. GRB 240905A: SVOM/GRM observation
  80. Fermi GRB 240905B: Global MASTER-Net observations report
  81. GRB 240905B: AstroSat CZTI detection and localization
  82. GRB 240825A: ATCA Detection of Radio Counterpart
  83. Swift GRB 240904A: Global MASTER-Net observations report
  84. GRB 240828A: SVOM/GRM observation
  85. Fermi Gamma-ray Burst Monitor trigger 240831A is not a GRB
  86. LIGO/Virgo/KAGRA S240902bq: Updated Sky localization
  87. GRB 240828A: GECAM detection
  88. LIGO/Virgo/KAGRA S240902bq: Identification of a GW compact binary merger candidate
  89. GRB 240825A: Magnitude Correction in SVOM/C-GFT Optical Observations
  90. GRB 240825A: MeerLICHT afterglow detection
  91. GRB 240828A: SAO RAS AS-500(2) optical observations
  92. GRB 240821A: VLT spectroscopic observations
  93. GRB 240825A: TSHAO Optical Upper Limit
  94. GRB 240829B: GRBAlpha detection
  95. GRB240828B: REM optical/NIR upper limits
  96. GRB 240828B: AbAO optical upper limit
  97. GRB 240825A: SOAR observations
  98. GRB 240828B: Mephisto optical upper limit
  99. GRB 240828B: GRANDMA Optical Upper Limit
  100. LIGO/Virgo/KAGRA S240830gn: Coverage and upper limits from MAXI/GSC observations

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