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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"

26294 results found.

  1. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  2. GRB 260818B: 6 GHz VLA observations
  3. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  4. GRB 260808B: SAO RAS observations of the optical rebrightening
  5. EP Alert 260820.31: Global MASTER-Net observations report
  6. GRB 260807A: EP-FXT follow-up observations
  7. GRB 260822A: SVOM/ECLAIRs refined analysis
  8. GRB 260809A: SVOM/ECLAIRs refined analysis
  9. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  10. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  11. GRB 260822A: EP/FXT follow-up observations
  12. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  13. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  14. EP260822a: EP-FXT non-detection and upper limit
  15. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  16. EP260822a: Einstein Probe detection of a fast X-ray transient
  17. GRB 260822A: LCO optical upper limits
  18. The EP-WXT trigger 01709287395 is likely a flaring star
  19. GRB 260822A: GROWTH-India Telescope Upper Limits
  20. GRB 260822A: SVOM detection of a short burst
  21. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  22. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  23. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 260818B: SVOM/C-GFT optical upper limit
  25. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  26. The EP-WXT trigger 01709286204 is likely a flaring star
  27. GRB 260818B: SVOM/GRM observation
  28. EP detected a brightening of LMXB 1ES 1735-26.9
  29. GRB 260818B: EP-FXT follow-up observation
  30. GRB 260818A: J-band observations with WINTER
  31. GRB 260818B: SVOM/ECLAIRs refined analysis
  32. GRB 260818A: SVOM/ECLAIRs refined analysis
  33. GRB 260818B: NOT optical upper limits
  34. GRB 260810A: SVOM/GRM observation
  35. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  36. GRB260818A: EP-FXT follow-up observation
  37. GRB 260818B: LCO optical upper limits
  38. GRB 260818B: SVOM detection of a short burst
  39. EP260806a: SAO RAS multicolor optical observations
  40. GRB 260818A: LCO optical upper limits
  41. EP260812a: AbAO optical upper limit
  42. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  43. GRB 260818A: SVOM possible detection of a long and faint GRB
  44. EP260806a: SVOM/ECLAIRs detection through targeted search
  45. EP260806a: NUTTELA-TAO optical observations
  46. The EP-WXT trigger 01709281429 is likely a flaring star
  47. EP260812a: AZT-22 optical upper limit
  48. EP260806a: WFST optical observations
  49. The EP-WXT trigger 01709280562 is likely a flaring star
  50. EP260812b: Optical upper limit with Kinder
  51. The EP-WXT trigger 01709279838 is likely a flaring star
  52. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  53. GRB 260808B: Liverpool Telescope further optical observations
  54. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  55. EP260812a: NOT and Liverpool Telescope upper limits:
  56. EP260812b: Liverpool Telescope observations
  57. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  58. EP260812a: SVOM/C-GFT optical upper limit
  59. EP260812b: COLIBRÍ optical observations
  60. EP260812b: SVOM/VT optical observation
  61. GRB 260808A: SVOM/GRM observation
  62. EP260812b: Einstein Probe detection of an X-ray transient
  63. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  64. GRB 260810A: Glowbug gamma-ray detection
  65. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  66. GRB 260810A: AstroSat CZTI detection of a long burst
  67. EP260812a: Einstein Probe detection of an X-ray transient
  68. GRB 260809A: SAO RAS optical observations
  69. GRB 260808B: SAO RAS optical observations
  70. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  71. GRB 260808A: GECAM-B observation
  72. GRB 260807A: SVOM/ECLAIRs refined analysis
  73. EP260806a: MAO/AZT-22 optical observations
  74. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  75. GRB260808B: MAO/AZT-22 optical observations
  76. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  77. GRB 260809A: J-band upper limit with WINTER
  78. GRB 260806A: Glowbug gamma-ray detection
  79. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  80. The EP-WXT trigger 01709278015 is likely a flaring star
  81. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  82. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  83. GRB 260809A: NOT optical observations
  84. GRB260809A: MAO/AZT-22 optical observations
  85. GRB260809A: OHP/T193 optical observations
  86. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  87. EP260809a: J-band upper limit with WINTER
  88. GRB 260808B: J-band upper limit with WINTER
  89. GRB 260808B: SVOM/ECLAIRs refined analysis
  90. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  91. GRB 260809A: SVOM detection of a faint burst
  92. GRB 260808B: Liverpool Telescope optical observations
  93. GRB 260808B: NOT optical observations
  94. GRB 260808B: LCO optical observations
  95. EP260809a: COLIBRÍ optical observations
  96. EP260809a: LCO optical observation
  97. EP260809a: OHP/T193 optical observations
  98. GRB260808B: OHP/T193 optical observations
  99. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  100. EP260809a: Einstein Probe detection of an X-ray transient

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