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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"

24992 results found.

  1. GRB 250101A: BOOTES-4/MET optical afterglow detection
  2. GRB 250101A: AKO Optical Afterglow Detection
  3. GRB 250101A: SAO RAS optical observations
  4. GRB 250101A: Enhanced Swift-XRT position
  5. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  6. GRB 250101A: SVOM/C-GFT early optical observations
  7. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  8. GRB 250101A: Nanshan/HMT optical observations
  9. GRB 250101A : GIT optical detection
  10. GRB 250101A: GMG Optical Observation
  11. GRB 250101A: Swift detection of a burst with an optical counterpart
  12. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  13. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  14. GRB 241229B: Continued CrAO ZTSh observations
  15. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  16. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  17. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  18. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  19. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  20. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  21. GRB 241229B: SVOM/GRM observation
  22. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  23. EP241217A: J band upper limit by SYSU 80cm telescope
  24. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  25. GRB 241229B: SAO RAS optical upper limit
  26. GRB 241228B: SAO RAS optical observations
  27. GRB 241229A: SAO RAS optical observations
  28. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 241229A: Swift-XRT observations
  30. EP240702a: 7DT Optical upper limits
  31. GRB 240606B: 7DT Optical upper limits
  32. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  33. GRB 241229B: Swift-BAT refined analysis
  34. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  35. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  36. GRB241229B: UVOT upper limits
  37. GRB 241228B: Fermi GBM Observation
  38. GRB 241228B: Swift-XRT afterglow detection
  39. GRB 241229B: Fermi GBM Observation
  40. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  41. GRB 241228A: Mondy optical afterglow observations
  42. GRB 241229A: GOTO optical upper limits
  43. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  44. GRB 241228A: NOT optical upper limits
  45. GRB 241228B: LCO optical observation
  46. GRB 241228A: Swift-BAT refined analysis
  47. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  48. GRB 241228A: Fermi GBM Observation
  49. GRB241228B: GROWTH-India Telescope optical observations
  50. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  51. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  52. GRB 241228A: GROWTH-India telescope optical upper limit
  53. GRB 241228B: TRT optical counterpart confirmation
  54. GRB 241228A: Swift-XRT refined Analysis
  55. GRB 241228A: Swift/UVOT Upper Limits
  56. GRB 241228A: Enhanced Swift-XRT position
  57. GRB 241228A: Swift detection of a burst
  58. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  59. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  60. GRB 241212A: VZLUSAT-2 detection
  61. EP241223a: Mondy AZT-33IK optical observations
  62. GRB 241029A: LCO optical observation
  63. GRB 241223A: Swift-XRT observations
  64. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  65. GRB 241029A: AbAO AS-32 optical observations
  66. GRB 241223A: Fermi GBM Detection
  67. Fermi trigger No 756678579: Global MASTER-Net observations report
  68. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  69. EP241223a
  70. EP241223a: EP-WXT detection of a fast X-ray transient
  71. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  72. GRB241113A: 7DT Optical upper limits
  73. GRB 241223A: GOTO optical observations summary
  74. GRB 241105A: JWST photometric observations of the host galaxy
  75. EP241217a: e-MERLIN radio observations
  76. GRB 241223A: BALROG localization (Fermi Trigger 756648531 / GRB 241223506)
  77. The EP-WXT trigger 01709129287 is likely a flaring star
  78. EP241217a: Liverpool Telescope optical upper limit
  79. EP241021a: VLA radio detection
  80. GRB 241218A: Mondy AZT-33IK optical upper limit
  81. EP241217a : Leavitt Observatory optical upper limit
  82. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  83. EP241217a: 1.6m Mephisto multi-band optical observations
  84. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  85. GRB 241218A: Swift/UVOT Upper Limits
  86. EP241217a: optical upper limit with the Liverpool Telescope
  87. GRB 241209B: EP-FXT afterglow detection
  88. GRB 241218A: NOT optical upper limits
  89. GRB 241218A: Swift-BAT refined analysis
  90. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  91. EP 241217a: NIR detection with P200/WIRC
  92. EP 241217a: Possible J-band detection with WINTER
  93. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  94. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  95. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  96. GRB 241217A / EP241217b: NOT optical upper limits
  97. GRB 241218A: REM optical upper limit
  98. GRB 241217A/EP241217b: REM optical/NIR upper limits
  99. EP241217a: REM optical/NIR upper limits
  100. GRB 241217a: Liverpool Telescope optical follow-up

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